M R S Internet Journal of Nitride Semiconductor Research

Volume 3, Article 30

Thermodynamic properties of group-III nitrides and related species


I. N. Przhevalskii
Russian Research Center "Applied Chemistry"

S. Yu. Karpov
Soft-Impact Ltd (St.Petersburg, Russia)

Yu. N. Makarov
Lehrstuhl für Strömungsmechanik, University of Erlangen-Nürnberg

This article was received on Friday, June 19, 1998 and accepted on Wednesday, September 30, 1998.

Abstract

A database for thermodynamic properties of group-III nitrides and relevant species involved into growth of these materials is developed in this paper. Standard formation enthalpies of materials and coefficients of polynomial approximations of the reduced Gibbs free energies are collected in the tables. They allow one to determine the Gibbs free energy, enthalpy, entropy and specific heat of a species as a function of temperature. The database covers solid and gaseous group-III nitrides, elemental species, gaseous metal-organic compounds, chlorides and hydrides of group-III elements, nitrogen containing precursors and organic byproducts of various chemical reactions proceeding during growth processes. Thermodynamic properties of adducts which can be formed in the vapor phase while mixing ammonia and metal-organic compounds are presented in the database as well. Much of the data given in this paper is presented for the first time. All the data are checked for self-consistency and therefore can be used for thermodynamic calculations.

1. Introduction

Group-III nitrides are semiconductor materials that are expected to play a revolutionary role in modern optoelectronics and high-power, high-temperature electronics. Development of the technological base for growth and processing of these materials demands detailed knowledge of their physical properties. Much effort has been made in the recent years to examine various characteristics and parameters of GaN, AlN, InN and their ternary compounds. Some carefully selected results are summarized in reference [1]. However, the scientific field related to group-III nitrides has broadened so quickly that the appearance of such books does not keep pace with the needs of the nitride community. More ongoing development of the reference database is desirable both for fundamental and applied studies covering growth, processing and characterization of these promising materials.

In this paper we make an attempt to develop a self-consistent database of thermodynamic properties of group-III nitrides and the species related to growth of these materials. Part of the data is taken from the reliable sources. The rest of the data are either refined using new information on the properties of the nitrides and relevant species available from the literature or presented here for the first time.

The organization of the paper is as follows. In Section 2 we explain the notation used throughout the paper and give the main expressions for calculation of thermodynamic functions of the materials. Section 3 gives a short guide to the database. In Section 4 we discuss the origin of the thermodynamic properties of the species refined or obtained in this paper.

2. Notation and general relationships

The Gibbs free energy G(P,T) of a certain species as a function of pressure P and temperature T is defined by the expression

(1)

where G0(P0,T) is the Gibbs thermodynamic potential taken at the standard pressure P0 = 1 atm. For G0(P0,T) we use the standard approximation accepted in the reference books [2] [3] [4]. According to these works the temperature dependence of G0(P0,T) can be approximated by a polynomial

(2)

Here H(298 K) is the standard formation enthalpy of the species (for elemental species this value is defined to be equal to zero) corresponding to the standard temperature T0 = 298.15 K, Φ(x) is the so called reduced Gibbs free energy. The polynomial approximation (2) differs from those used in JANNAF tables or in well-known database “Chemkin”. By special comparison we have found that our polynomial form provides more a more accurate approximation of the thermodynamic properties of various species in a wide temperature range.

Using the array of coefficients ϕ,ϕ-2...ϕ3 one can calculate the enthalpy H(T) , entropy S(T) and specific heat Cp(T) of the species corresponding to the standard pressure P0 = 1 atm and arbitrary temperature

(3)

In this paper thermodynamic functions of materials are calculated by commonly accepted methods discussed in detail in [2]. For gaseous species the molecular constants (bond lengths, angles between the bond directions, oscillation frequencies etc.), either taken from literature or estimated (in the case of lack of experimental information), are used in the calculations. Therewith the "rigid rotator - harmonic oscillator" approximation is applied to account for internal rotational degrees of freedom of molecules.

3. Organization of the database

For convenience the thermodynamic database of the materials involved into growth of group-III nitrides is split into seven tables [1]. In Table 1 the data on elemental materials are collected. Table 2 and Table 3 contain the data on group-III hydrides and chlorides respectively. Table 4 presents the data on gaseous group-III metal-organic compounds. In Table 5 the data on various (first of all, gaseous) species which are either nitrogen carrying precursors or byproducts of chemical reactions are given. Table 6 contains thermodynamic properties of the adducts forming during MOVPE or HVPE growth of group-III nitrides. And, finally, in Table 7 properties of solid and gaseous binary nitrides are presented. Every table contains in separate columns —

Thermodynamic properties of 44 species - Al(s), Al(l), Al(g), Al2(g), AlH(g), AlH2(g), AlH3(g), AlN(g), CH(g), CH2(g), CH3(g), CH4(g), s-C2H2(g), C2H4(g), C2H5(g), C2H6(g), Cl(g), Cl2(g), H(g), H2(g), HCl(g), HN3(g), In(s), In(l), In(g), InH(g), Ga(s), Ga(l), Ga(g), GaH(g), GaCl(g), GaCl2(g), GaCl3(s), GaCl3(l), GaCl3(g), Ga2Cl6(g), N(g), N2(g), NH(g), NH2(g), NH3(g), N2H2(g), N2H4(g), NH4Cl(s) - are taken from references [2] [3] [4] [5]. For these components no special comments will be made. The properties of 31 other species (including adducts forming during MOVPE and HVPE process) - AlN(s), AlCH3(g), Al(CH3)3(g), Al2(CH3)6(g), a-C2H2(g), GaH2(g), GaH3(g), GaN(s), GaN(g), GaCH3(g), Ga(CH3)3(g), InH2(g), InH3(g), InN(s), InCH3(g), In(CH3)3(g), Al·NH3(g), AlCH3·NH(g), (AlCH3·NH)3(g), Al(CH3)3·NH3(g), (Al(CH3)2·NH2)3(g), (Al·N)3 , (Al(CH3)2·NH2)2(Ga(CH3)2·NH2)(g), (Al(CH3)2·NH2)(Al(CH3)2·NH2)2(g), Ga·NH3(g), GaCH3·NH(g), Ga(CH3)3·NH3(g), (GaCH3·NH)3(g), (Ga(CH3)2·NH2)3(g), (Ga·N)3 , GaCl3·NH3(g) - are either refined or derived in this paper. For these species the thermodynamic data are attended by necessary comments given in Section 4.

All the data are verified for self-consistency and therefore can be used for thermodynamic calculations.

4. Comments

In this section we make short comments on the thermodynamic properties of various species and the way in which these properties are estimated. The main species are arranged in alphabetical order, the adducts are considered at the end of section.

4.1. AlCH3(g) monomethylaluminum (MMA)

Molecules AlCH3 (MMA) have been observed experimentally in the gas phase [6]. Thermodynamic functions of MMA are obtained using molecular constants calculated theoretically in references [7] [8] [9]. According to these works the molecule MMA in the ground X1A1 state has the structure of C3V symmetry. Formation enthalpy of MMA is calculated using the value of Al-CH3 bond energy estimated by comparison of the bond energies in such pairs of molecules as AlCH3 and GaCH3 , Al(CH3)3 and Ga(CH3)3. This procedure is applied because theoretical estimation of the formation enthalpy of MMA carried out in reference [7] results in an evidently underestimated value (this was mentioned by authors of reference [7] themselves). Our data are in a reasonable agreement with those obtained in reference [10].

4.2. Al(CH3)3(g) trimethylaluminum (TMA)

Thermodynamic functions of Al(CH3)3 are calculated using the molecular constants taken from experimental [11] [12] [13] [14] [15] [16] [17] and theoretical [11] studies. According to these works, the TMA molecule in the ground X1A1 state has the structure of D3h symmetry. The formation enthalpy of TMA is taken after reference [18]. Earlier thermodynamic functions of TMA were calculated in reference [19] using approximate values of molecular constants and in reference [10]. Our data are in a reasonable agreement with the results of both these works.

4.3. Al2(CH3)6(g)

Thermodynamic properties of gaseous Al2(CH3)6 are calculated using the molecular constants obtained experimentally in references [13] [15] [16] [17] [20] [21]. According to these works the Al2(CH3)6 molecule in the ground X1A1 state has the structure of D2h symmetry. The formation enthalpy of Al2(CH3)6 is taken from reference [18].

Earlier thermodynamic functions of Al2(CH3)6 were calculated in reference [19] using approximate values of molecular constants and in reference [10]. The value of entropy at 298.15 K given in [10] is lower than that accepted in the current work. The cause of the discrepancy could not be revealed since the authors of reference [10] did not refer to their source of data on molecular constants. The formation enthalpy of Al2(CH3)6 reported in reference [10] is somewhat lower than that recommended in reference [18], although it remains within the experimental error bars.

4.4. AlN(s)

The specific heat Cp(T) of solid AlN has been measured by different groups in the temperature range of 50-300 K. The results are summarized in reference [1] and plotted in Figure 1 (numerical values are given also in the Data file 1). These data were used in references [4] [5] for calculation of thermodynamic functions of solid AlN. We refine the thermodynamic properties of AlN accounting for the results of AlN specific heat measurements carried out in the temperature range of 2.6-300 K [22] (the data on specific heat are shown in Figure 1 and also given in the Data file 2). The formation enthalpy of AlN is taken according to references [4] [5].

Free evaporation of AlN in vacuum has been investigated in reference [23]. The evaporation of AlN is found to be congruent. The total pressure of evaporating species (Al and N2) measured at different temperatures is shown in Figure 2 and numerical data given in Data file 3. Comparison to thermodynamic calculations (the solid line in Figure 2) shows that the evaporation of AlN is kinetically limited. Due to this kinetic effect the experimental data on AlN evaporation can not be used for estimation of thermodynamic properties of this compound.

4.5. a-C2H2(g) vinylidene

Thermodynamic properties of vinylidene are calculated using the molecular constants found in theoretical and experimental studies [24] [25]. According to the results of these studies the vinylidene molecule has a configuration of C2V symmetry in the ground state. The formation enthalpy of vinylidene is determined using the formation enthalpy of s-C2H2(g) [4] and the isomerization energy of acetylene- vinylidene - 43 kcal/mol obtained in references [24] [25]

4.6. GaCH3 monomethylgallium (MMG)

Thermodynamic functions for gaseous GaCH3 (MMG) are calculated using molecular constants determined in experimental [26] and theoretical [27] [28] [29] studies of the molecules MMG and CH3GaH [30] [31]. According to these works the molecule GaCH3 in the ground X1A1 state has the configuration of C3V symmetry. The formation enthalpy of MMG is calculated using the value of the Ga-CH3 bond energy determined while studying the pyrolysis of trimethylgallium (Ga(CH3)3) [32] [33]. Theoretical calculation of this energy [27] gave a remarkably underestimated value. Earlier thermodynamic functions of MMG were reported in reference [10]. Our data are in a reasonable agreement with the results of this work.

4.7. Ga(CH3)3(g) trimethylgallium (TMG)

Thermodynamic functions of gaseous Ga(CH3)3 (TMG) are calculated using the molecular constants determined both experimentally [13] [34] [35] [36] [37] and theoretically [27] [28]. According to these studies the TMG molecule in the ground X1A1 state has the configuration of D3h symmetry. Formation enthalpy of TMG is taken from reference [18]. Earlier thermodynamic properties of TMG have been estimated in [38] and [10] using the approximate values of the molecular constants. Our data agree with the results obtained in reference [10].

4.8. GaH2(g)

Molecular constants of gaseous GaH2 are determined using the experimental data of references [30] [39] [40] [41] and results of theoretical calculations carried out for molecules GaH2 [30] [39] [40] [31] [42] [43] [44] and Ga2H4 [45]. According to the experimental and theoretical results the molecule GaH2 in the ground state X2A1 has a non-linear configuration of C2V symmetry. We calculate the formation enthalpy of GaH2 using the value of Ga-H bond energy in the molecule GaH2 obtained theoretically in [44] [46]. Recently thermodynamic functions of GaH2 have been estimated in Reference [10]. The authors of [10] reported the value of entropy of GaH2 at 298.15 K as well as the polynomial approximation of the specific heat which agree well with our estimates. However, the formation enthalpy of GaH2 - H(298 K) = 164 kJ/mol accepted in [10] exceeds significantly the value obtained in this work. This is related to overestimation in reference [10] the Ga-H bond energy in the molecule GaH2 - 273.6 kJ/mol instead 171.5 kJ/mol as follows from the theoretical calculations of references [44] [46].

4.9. GaH3(g)

Molecular constants of gaseous GaH3 are taken from experimental [39] [47] and theoretical [39] [43] [44] [47] [48] [49] [50] [51] [52] [53] studies of molecules GaH3 and Ga2H6 [48] [49]. According to the results obtained in these works the molecule GaH3 in the ground state X1A1 has a flat configuration of D3h symmetry. We calculate the formation enthalpy of GaH2 using the value of Ga-H bond energy in the molecule GaH3 obtained theoretically in reference [44] [46]. Thermodynamic functions of gaseous GaH3 have been reported also in reference [10]. The value of entropy of GaH3 at 298.15 K and the polynomial approximation for specific heat agree well with our data. The formation enthalpy of GaH3 - H(298 K) = 108 kJ/mol accepted in reference [10] is significantly less than the value obtained in this work. This is related to the underestimation in reference [10] of the Ga-H bond energy in the molecule GaH3 - 273.6 kJ/mol instead 338.7 kJ/mol predicted based on theoretical calculations [44] [46].

4.10. GaN(s)

The specific heat Cp(T) of solid GaN has been measured by calorimetry in the temperature interval of 5-60 K [54] and in the temperature interval of 55-300 K [55]. The experimental data obtained in these works are shown in Figure 3 and given numerically in Data file 4. For comparison in Figure 3 is shown the approximation of the specific heat versus temperature recommended in reference [1].

Thermodynamic properties of solid GaN are determined using the experimental data on specific heat [22] [54] [55] and the enthalpy increment of GaN [56]. We take the formation enthalpy of GaN averaged over two values - one of them based on the calorimetric measurements of GaN heat of burning [57], the other obtained using the 3rd law and the experimental data of reference [58]. The value accepted in reference [18] is an underestimate. This was pointed out by authors of reference [59], where results of reference [57] were discussed in regard to the determination of the formation enthalpy of solid InN. The thermodynamic functions of GaN reported in references [60] [61] were obtained using rough estimates of the GaN specific heat, entropy and formation enthalpy; therefore they are not quite accurate.

Langmuir (free) evaporation of GaN in vacuum has been studied in reference [62]. The evaporation was found to be congruent. The total pressure of the evaporating species (Ga and N2) was measured versus temperature by a torsion-effusion method. The results of the measurements are plotted in Figure 4 and given numerically in Data file 5. Comparison to thermodynamic calculations (the solid line in Figure 4) shows that the evaporation of GaN is kinetically limited. Due to this limitation the experimental data on GaN evaporation can not be used for estimation of the thermodynamic properties of this compound.

4.11. GaN(g)

There is no information on the molecular constants of gaseous GaN. To calculate the thermodynamic functions of GaN(g) we use the oscillation frequencies and interatomic distance estimated in references [63] [64] assuming by analogy with AlN(g) that the ground state of GaN molecule is X2Π. The formation enthalpy of gaseous GaN is calculated by using the dissociation energy of the molecule equal to 523 kJ/mol as determined in reference [65]. Thermodynamic functions of gaseous GaN reported in reference [63] have been calculated using the molecular constants obtained in references [63] [64]. The formation enthalpy of GaN(g) was not determined in reference [63].

4.12. InCH3 monomethylindium (MMI)

We could not find in the literature any information on the molecular constants of gaseous InCH3 (MMI). That is why we estimate these constants assuming in analogy with MMA and MMG that the MMI molecule in the ground state X1A1 state has the configuration of C3V symmetry. The formation enthalpy of MMI is found using the value of In-CH3 bond energy extracted in reference [66] from the experimental data on pyrolysis of In(CH3)3.

4.13. In(CH3)3(g) trimethylindium (TMI)

Thermodynamic functions of gaseous In(CH3)3 (TMI) are calculated using the molecular constants obtained in experimental studies [34] [67] [68] [69] [70] [71] [72]. According to these works the TMI molecule in the ground X1A1 state has the configuration of D3h symmetry. To determine the value of formation enthalpy of TMI we use the experimental data on the formation enthalpy of solid In(CH3)3 as well as the heat of In(CH3)3(s) sublimation [73] [74]. Earlier rough estimations of thermodynamic properties of TMI have been made in reference [75].

4.14. InH2(g)

Thermodynamic functions of gaseous InH2 are calculated on the base of molecular constants measured in references [39] [40] and theoretically calculated in reference [40]. According to these works the molecule InH2 in the ground X2A1 state has non-linear configuration of C2V symmetry. The formation enthalpy of InH2 is estimated using the value of In-H bond energy in the InH2 molecule calculated in reference [76].

4.15. InH3(g)

The thermodynamic functions of gaseous InH3 are calculated using the molecular constants determined in experimental [39] [47] and theoretical studies [40]. According to these works the molecule InH3 in the ground X1A1 state has a flat configuration of D3h symmetry. The formation enthalpy of InH3 is estimated using the value of the In-H bond energy in the InH3 molecule calculated in reference [76].

4.16. InN(s)

There is no experimental information on thermodynamic properties of solid InN. The published data on InN evaporation [77] [78] [59] [79] cannot be used to determine the enthalpy of InN formation since equilibrium conditions were not met in these experiments. Evaporation of InN occurs with decomposition into the liquid and gas phases starting at least from 450oC [22]. No experimental data on Langmuir evaporation of InN in vacuum are available at the present time.

The value of H(298 K) estimated using the heat of InN burning [57] and accepted in [58] is apparently underestimated (this was mentioned by the authors of reference [59] who especially analyzed the work [57]) and cannot serve as the basis for estimation of properties of InN. That is why we take the available data on the properties of other III-V compounds and use the analogy method [80] to extrapolate the respective thermodynamic functions of InN.

4.17. Adducts formed while mixing gaseous group-III compounds and ammonia

Spectral investigations of the chemical reactions between Al atoms in a ground electron state and NH3 molecules [81], theoretical studies of Al·NH3 adducts [82] [83] and numerous experimental data [84] [85] [86] [87] [88] [89] [90] [91] [92] [93] [94] [95] [96] [97] [97] [98] [99] [100] provide evidence of the formation in the gaseous mixture of metal-organic group-III compounds and ammonia of such adducts as TMA·NH3 and TMG·NH3 . With gradual liberation of methane these adducts transform into the radicals DMA·NH2 and DMG·NH2 which, in turn, can combine into the complexes (DMA·NH2)3 , (DMG·NH2)3 , (DMA·NH2)2(DMG·NH2) and (DMA·NH2)(DMG·NH2)2 . Further liberation of CH4 molecules is assumed from these complexes with their transition into (MMA·NH)3 , (MMG·NH)3 , (MMA·NH)2(MMG·NH) , (MMA·NH)(MMG·NH)2 , and then into gaseous polymers of (Al·N)3 , (Ga·N)3 , (Al·N)2(Ga·N) , (Al·N)(Ga·N)2 type. Below the thermodynamic properties of some of these adducts are estimated. In addition the properties of GaCl3·NH3 , which can be formed during hydride vapor phase epitaxy of GaN, are discussed.

4.17.1. AlNH3(g)

The molecular constants of gaseous Al·NH3 necessary for estimation of thermodynamic functions are taken from theoretical studies [82] [83]. According to these works the molecule Al·NH3 in the ground X1A1 state has configuration of C3V symmetry. The formation enthalpy of Al·NH3 is found using the value of Al-NH3 bond energy calculated theoretically in [82] [83].

4.17.2. GaNH3(g)

There is no information on molecular constants of the gaseous Ga·NH3 adduct. In analogue with Al·NH3 we assume that molecule Ga·NH3 is stable in the ground X1A1 state and has the structure of C3V symmetry. Molecular constants of Ga·NH3 are found by extrapolation of the corresponding constants for the pairs TMA and TMG, TMA·NH3 and TMG·NH3 , Al·NH3 and Ga·NH3 . The formation enthalpy of Ga·NH3 is calculated using the estimated value of the Ga-NH3 bond energy. The estimation procedure is based on a comparison of the values of bond energies in the pairs of molecules Al·NH3 and Ga·NH3 , TMA·NH3 and TMG·NH3 .

4.17.3. Al(CH3)3·NH3(g)

Thermodynamic functions of gaseous Al(CH3)3·NH3 (or TMA·NH3) are calculated using the molecular constants found both experimentally [84] [85] [86] [87] and theoretically [86] [101] [102]. According to these studies the molecule Al(CH3)3·NH3 in the ground X1A1 state has the configuration of C3V symmetry. The formation enthalpy of Al(CH3)3·NH3 is determined using the value of TMA-NH3 bond energy obtained in references [86] [87] [102] [103] [104] [105].

4.17.4. Ga(CH3)3·NH3(g)

Molecular constants of gaseous Ga(CH3)3·NH3 (or TMG·NH3) needed for estimation of the thermodynamic functions are taken from experimental studies [88] [89] [90] [91] [92] [93] [94] [95]. According to the results of these works the molecule Ga(CH3)3·NH3 in the ground X1A1 state has the structure of C3V symmetry. The formation enthalpy of Ga(CH3)3·NH3 is obtained through the TMG-NH3 bond energy determined in references [104] [96].

4.17.5. (Al(CH3)2·NH2)3(g)

Thermodynamic properties of (Al(CH3)2·NH2)3 or (DMA·NH2)3 are calculated using the molecular constants taken from experimental studies of (DMA·NH2)3 [100], (DMG·NH2)3 [97] [98], (DMA·NH2)2 [97], TMA·NH3 , TMG·NH3 and theoretical investigations of DMA·NH2 [86] and (HAl·NH)3 [106]. In accordance with these works it is accepted that in the ground state X1A the complex (DMA·NH2)3 has non-flat ring configuration of C1 symmetry. The formation enthalpy of (DMA·NH2)3 is found using the experimental data of reference [103].

4.17.6. (Ga(CH3)2·NH2)3(g)

Thermodynamic properties of (Ga(CH3)2·NH2)3 or (DMG·NH2)3 are calculated using the molecular constants taken from experimental studies of (DMG·NH2)3 [97] [98], (DMG·NH2)2 [97], and TMG·NH3 . According to these works the complex (DMG·NH2)3 in the ground state X1A has non-flat ring configuration of C1 symmetry. There is no information on the formation enthalpy of (DMG·NH2)3. We estimate this value by comparison the formation energies of the pairs (DMA·NH2)3 and (DMG·NH2)3 , TMA·NH3 and TMG·NH3 .

4.17.7. (Al(CH3)2·NH2)2(Ga(CH3)2·NH2)(g) and (Al(CH3)2·NH2)(Ga(CH3)2·NH2)2(g)

The complexes (Al(CH3)2·NH2)2(Ga(CH3)2·NH2) and (Al(CH3)2·NH2)(Ga(CH3)2·NH2)2 have not been studied. The molecular constants of these species as well as their formation enthalpies are calculated using extrapolation of corresponding data on the properties of (Al(CH3)2·NH2)3 and (Ga(CH3)2·NH2)3 adducts.

4.17.8. AlCH3NH(g) and GaCH3NH(g)

Decomposition of TMA·NH3 and TMG·NH3 can lead to appearance of gaseous radicals AlCH3·NH and GaCH3·NH which, in turn, can combine into the ring complexes (AlCH3·NH)3 and (GaCH3·NH)3 . There is no information on molecular constants of these species in literature. We estimate them using corresponding data obtained for molecules TMA·NH3 , TMG·NH3 , DMA·NH2 , DMG·NH2 , MMA, MMG, Al·NH3 , Ga·NH3 , HGaCH3 and HAlCH3 . Therewith we assume that molecules AlCH3·NH(g) and GaCH3·NH(g) in the ground X1A state have an asymmetric configuration of C1 symmetry. The formation enthalpies of AlCH3·NH(g) and GaCH3·NH(g) are estimated based on experimental data for TMA·NH3 and TMG·NH3 decomposition obtained in references [86] [103] [99].

4.17.9. (AlCH3·NH)3(g) and (GaCH3·NH)3(g)

Thermodynamic functions of gaseous (AlCH3·NH)3 and (GaCH3·NH)3 are calculated based on molecular constants estimated using results of experimental and theoretical studies of (AlH·NH)3 , (DMA·NH2)3 , (DMG·NH2)3 , (DMG·NH2)2(DMA·NH2) , TMA·NH3 and TMG·NH3 . Therewith is assumed that molecules considered in their ground states have asymmetric configuration of C1 symmetry. The formation enthalpies are estimated using the results of study of TMA·NH3 and TMG·NH3 decomposition accompanied by release of methane [86] [103] [99].

4.17.10. (AlN)3 and (GaN)3

Ring molecular complexes (Al·N)3 and (Ga·N)3 are assumed to be the final products in the chain of consequent adduct formation when mixing group-III metal-organic compounds and ammonia. The thermodynamic functions of these molecules are calculated using the estimated values of molecular constants. For this we use the results of experimental and theoretical studies of AlH·NH3 [106], (BH·NH)3 [4] and (B·N)3 [107] [108]. We also assume that in their ground states the molecules (Al·N)3 and (Ga·N)3 have a flat structure of D3h symmetry. Formation enthalpies of (Al·N)3 and (Ga·N)3 are estimated on the base of studies of TMA·NH3 and TMG·NH3 decomposition with simultaneous release of methane [86] [103] [99].

4.17.11. GaCl3·NH3

Thermodynamic properties of GaCl3·NH3 are calculated using the molecular constants experimentally found in [109] [110]. According to these works the GaCl3·NH3 molecule has in the ground state X1A1 a configuration of C3V symmetry. The formation enthalpy of GaCl3·NH3 is determined using the value of formation enthalpy of solid GaCl3·NH3 as well as the evaporation enthalpy of liquid GaCl3·NH3 recommended in [18]. The enthalpy of GaCl3·NH3(s) melting necessary for the calculations is estimated by a method proposed in reference [111].

5. Summary

In conclusion, a database of thermodynamic properties of group-III nitrides and substances related to growth of these materials is developed in this paper. A polynomial approximation of the reduced Gibbs free energy as a function of temperature corresponding to the standard pressure of 1 atm is given for 75 species. Among them data for 31 species (including adducts frequently formed during vapor phase epitaxy) are either refined or obtained here for the first time. Using the polynomial one can calculate temperature dependencies of enthalpy, entropy and specific heat of a certain species. The database is checked for self-consistency and therefore can be used for thermodynamic calculations.

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Table 1

Thermodynamic properties of elemental materials related to growth of group-III nitrides.
Component Phase Temperature range (K) H(298K) J/mol ϕ0 ϕ ϕ-2 ϕ-1 ϕ1 ϕ2 ϕ3 reference
Al s 298.15-933.61 0 172.8289 50.51806 -0.00411847 1.476107 -458.1279 2105.75 -4168.337 [4]
Al l 933.61-3000 0 103.0714 26.00912 0.008181946 -0.4129445 32.24031 -43.76215 30.68377 [4]
Al g 298.15-3000 329700 217.0413 20.81346 0.000249045 0.60354813 -0.2495735 0.5140443 -0.5629165 [4]
Al2 g 298.15-3000 490380 353.35 48.47124 -0.00369942 1.6604767 -42.89068 106.9097 -115.6532 [4]
Ga s 100-302.91 0 241.3354 66.94004 -0.00324457 1.676481 -602.4515 0 0 [4]
Ga l 302.91-3000 0 126.5938 26.24945 0.001124295 0.1477694 -3.306797 7.960486 -4.117994 [4]
Ga g 298.15-3000 271979 268.3674 38.19512 -0.00269398 1.226597 -118.8071 194.3493 -161.9061 [4]
In s 100-429.78 0 28.56306 0.173385 0.001116428 0.3581493 621.9059 -2378.554 0 [4]
In l 429.78-3000 0 136.5535 27.6628 0.002004388 0.3864998 -7.11553 11.33041 -2.563969 [4]
In g 298.15-3000 240389 179.4259 5.544982 0.002369352 0.1624565 199.5227 -392.3531 350.0412 [4]
Cl g 298.15-3000 121302 230.4749 26.0518 -0.001404393 0.8484566 -26.44172 33.95742 -23.09449 [2]
Cl2 g 298.15-3000 0 315.6297 37.6554 -0.001818968 1.2427151 -0.7480257 -3.237695 19.2696 [2]
H g 298.15-3000 217998 166.7375 20.75064 0.000011002 0.61825525 0.3951741 -0.9575932 1.072888 [2]
H2 g 298.15-3000 0 205.5368 29.50487 0.000168424 0.86065612 -14.95312 78.18955 -82.78981 [2]
N g 298.15-3000 472680 205.2031 20.71029 0.000020737 0.61679049 0.9006424 -2.39269 3.047489 [2]
N2 g 298.15-3000 0 242.8156 21.47467 0.001748786 0.5910039 81.08497 -103.6265 71.30775 [2]

Table 2

 Thermodynamic properties of group-III hydrides.
Component Phase Temperature range (K) H(298K) J/mol ϕ0 ϕ ϕ-2 ϕ-1 ϕ1 ϕ2 ϕ3 reference
AlH g 298.15-3000 248949 241.7735 23.45061 0.000267033 0.7561976 94.52152 -149.8564 133.8216 [4]
AlH2 g 298.15-3000 247058 263.5826 24.47025 0.000052127 0.887457 201.8884 -305.6576 247.8367 [4]
AlH3 g 298.15-3000 208143 247.6922 25.23092 -0.00247941 1.1974457 351.8847 -534.7299 424.2375 [4]
GaH g 298.15-3000 214301 256.9793 24.75093 -0.00017796 0.81698595 85.2476 -130.322 112.485 [4]
GaH2 g 298.15-3000 261000 283.1801 27.73824 -0.00098536 1.04260905 189.6211 -292.8738 234.49034
GaH3 g 298.15-3000 140000 262.5014 25.64802 0.000707271 1.05328668 360.1502 -557.6752 447.1876
InH g 298.15-3000 214704 268.5535 26.25779 -0.00068009 0.88853891 77.20851 -119.0338 104.2369 [4]
InH2 g 298.15-3000 301000 300.4066 30.93877 -0.00176795 1.1772364 174.5085 -275.3281 224.5262
InH3 g 298.15-3000 226000 298.3732 36.02385 -0.00383638 1.5631789 294.7202 -457.1725 368.1224

Table 3

 Thermodynamic properties of group-III chlorides.
Component Phase Temperature range (K) H(298K) J/mol ϕ0 ϕ ϕ-2 ϕ-1 ϕ1 ϕ2 ϕ3 reference
GaCl g 298.15-3000 -70553 332.2718 37.11052 -0.000746187 1.1606512 4.891346 -4.467591 5.506236 [4]
GaCl2 g 298.15-3000 -241238 443.2976 57.74584 -0.002265112 1.8755545 3.66186 -9.356338 15.88245 [4]
GaCl3 s 298.15-351 -525000 117.602 22.661 0 1.768938 1229.9 0 0 [4]
GaCl3 l 351.-1000 -525000 426.622 105.0455 0.000857935 2.0378948 55.82225 -187.023 316.5247 [4]
GaCl3 g 298.15-3000 -431573 526.8113 82.03355 -0.003486473 2.6855923 8.278878 -14.5678 12.8899 [4]
Ga2Cl6 g 298.15-3000 -957552 945.776 180.9567 -0.007721776 5.923436 14.74793 -26.29971 23.6243 [4]

Table 4

 Thermodynamic properties of group-III metal-organic compounds.
Component Phase Temperature range (K) H(298K) J/mol ϕ0 ϕ ϕ-2 ϕ-1 ϕ1 ϕ2 ϕ3 reference
AlCH3 g 298.15-3000 70000 305.5526 35.03927 -0.00174578 1.4497961 350.8434 -441.7573 302.0432
Al(CH3)3 g 298.15-3000 -87864 439.3127 67.03525 -0.00997983 3.579156 1117.969 -1438.63 1005.325
Al2(CH3)6 g 298.15-3000 -268000 732.0682 153.8187 -0.02210495 7.934453 2291.222 -2980.321 2100.53
GaCH3 g 298.15-3000 79000 310.9298 33.36529 -0.00299805 1.4928029 363.5709 -463.8545 321.0485
Ga(CH3)2 g 298.15-3000 78000 420.9466 58.61963 -0.00830238 2.828981 634.9377 -719.8074 425.8506
Ga(CH3)3 g 298.15-3000 -45100 419.6335 56.51964 -0.00623311 3.1207383 1253.185 -1835.496 1583.225
InCH3 g 298.15-3000 215000 327.9518 37.02704 -0.00234819 1.5345267 331.9569 -408.1081 273.5027
In(CH3)3 g 298.15-3000 207000 486.1998 75.34946 -0.00966392 3.760722 1060.398 -1344.147 926.5466

Table 5

 Thermodynamic properties of compound species related to growth of group-III nitrides. (*) Indexes s- and a- denotes the molecules C2H2 having different bond configurations: HC=CH and H2C=C respectively.
Component Phase Temperature range (K) H(298K) J/mol ϕ0 ϕ ϕ-2 ϕ-1 ϕ1 ϕ2 ϕ3 reference
CH g 298.15-3000 597370 242.7524 24.00883 0.001670102 0.6407824 37.86651 15.51023 -45.27447 [3]
CH2 g 298.15-3000 390421 240.600 20.52894 0.002739503 0.5603418 152.657 -143.930 66.92434 [3]
CH3 g 298.15-3000 146300 235.311 21.73794 0.001495276 0.7668275 260.1063 -286.5025 170.8566 [3]
CH4 g 298.15-3000 -74600 160.1245 0.1376158 0.003060968 0.2359966 530.4743 -641.3777 443.8204 [3]
s-C2H2* g 298.15-3000 227400 290.1858 41.22485 -0.00318242 1.5993697 185.8367 -182.5197 98.56432 [3]
a-C2H2* g 298.15-3000 406000 295.9776 34.44796 -0.000729682 1.2620663 225.396 -274.2221 181.7939
C2H4 g 298.15-3000 52400 235.4331 20.90119 -0.004640969 1.384579 557.1087 -729.554 519.1573 [3]
C2H5 g 298.15-3000 107000 232.3991 10.06969 -0.00231435 1.0455083 730.0119 -972.2628 700.7000 [3]
C2H6 g 298.15-3000 -84000 210.8502 12.79009 -0.00332157 1.28072185 834.093 -1099.041 784.2161 [3]
HCl g 298.15-3000 -92310 243.9878 23.15984 0.001819985 0.6147384 51.16604 -36.89502 9.174252 [2]
HN3 g 298.15-3000 294000 318.1457 37.99594 -0.003275438 1.5385397 231.3021 -308.8172 225.2746 [2]
NH4Cl s 298.15-1500 -314553 1655.076 514.7979 -0.05652215 14.5633 -6619.275 24457.48 -41827.86 [5]
NH3 g 298.15-3000 -45940 231.1183 20.52222 0.000716251 0.7677236 244.6296 -251.69 146.6947 [2]
NH2 g 298.15-3000 190000 242.1951 21.06781 0.002580563 0.5819481 147.4422 -141.0088 79.39323 [2]
NH g 298.15-3000 338885 241.3573 24.14921 0.001711517 0.6418191 38.52613 -13.20793 -8.079821 [2]
N2H2 g 298.15-3000 211860 259.887 22.8261 -0.000935 0.966786 245.36 -151.638 0 [2]
N2H4 g 298.15-3000 95180 301.5557 37.05947 -0.006113206 1.8485832 412.1844 -493.5967 319.4443 [2]

Table 6

 Thermodynamic properties of adducts related to growth of group-III nitrides.
Component Phase Temperature range (K) H(298K) J/mol ϕ0 ϕ ϕ-2 ϕ-1 ϕ1 ϕ2 ϕ3 reference
Al·NH3 g 298.15-3000 250000 348.4526 41.86005 0.000211864 1.4472277 255.1086 -257.7037 141.7346
(Al·N)3 g 298.15-3000 -525000 543.3702 108.7302 -0.01831327 4.594580 171.8226 -290.5235 248.8242
MMA·NH g 298.15-3000 -190000 414.2169 61.61885 -0.00253783 2.3779207 423.3068 -509.5931 332.8755
(MMA·NH)3 g 298.15-3000 -750000 892.3664 202.2196 -0.03836758 9.739639 1407.448 -1800.317 1257.067
TMA·NH3 g 298.15-3000 -246000 588.4401 112.231 -0.01885472 5.621111 1273.086 -1552.79 1055.969
(DMA·NH2)3 g 298.15-3000 -760000 1195.758 324.3533 -0.06284943 15.81051 2406.101 -2903.563 1950.622
Ga·NH3 g 298.15-3000 200000 353.3958 40.79851 0.000266934 1.4191327 264.0403 -272.4233 153.5392
(Ga·N)3 g 298.15-3000 -360000 609.4856 122.2825 -0.01653284 4.809612 77.69752 -1333.739 1154.612
MMG·NH g 298.15-3000 -130000 418.7216 60.2648 -0.00183430 2.3002024 434.3678 -528.0146 347.8084
(MMG·NH)3 g 298.15-3000 -520000 946.5981 213.6344 -0.03663681 9.919197 1347.501 -1711.188 1184.161
TMG·NH3 g 298.15-3000 -170000 530.7141 87.98152 -0.00725578 4.304382 1467.071 -1874.727 1297.835
(DMG·NH2)3 g 298.15-3000 -525000 1021.0 264.9086 -0.04829547 13.504477 2918.077 -3839.803 2751.129
(DMA·NH2)2(DMG·NH2) g 298.15-3000 -680000 1129.111 302.3056 -0.05821187 15.004891 2596.184 -3249.624 2246.259
(DMA·NH2) (DMG·NH2)2 g 298.15-3000 -600000 1084.095 285.9634 -0.05281923 14.281768 2738.584 -3512.749 2471.468
GaCl3·NH3 g 298.15-3000 -619000 602.7288 99.90594 -0.003368528 3.512104 365.2924 -445.3745 295.2586

Table 7

 Thermodynamic properties of group-III nitrides.
Component Phase Temperature range (K) H(298K) J/mol ϕ0 ϕ ϕ-2 ϕ-1 ϕ1 ϕ2 ϕ3 reference
AlN s 298.15-2000 -319000 124.0509 45.23707 -0.00732285 1.861658 25.72751 -26.7394 39.61092
AlN g 298.15-3000 438530 307.9826 32.62139 -0.00060462 1.0388258 25.05068 29.55234 -64.15543 [4]
GaN s 298.15-2000 -114000 160.2647 52.86351 -0.00799055 2.113389 1.313428 -2.441129 1.945731
GaN g 298.15-3000 221659 313.033 33.77197 -0.00212262 1.1675484 25.48238 -42.78832 36.53425
InN s 298.15-1400 -71000 182.0219 58.73762 -0.00885117 2.347111 2.118085 -2.740333 -1.525678

Table 1s

 Thermodynamic properties of elemental materials related to growth of group-III nitrides (ChemKin format).
Component Phase a1 a2 a3 a4 a5 a6 a7 reference
Al s 0.19463122E+01 0.57014083E-02 -0.11246948E-04 0.11906191E-07 -0.40549592E-11 -0.75595051E+03 -0.89767193E+01 [4]
Al l 0.38186714E+01 0.35092866E-13 -0.29243825E-16 0.10296049E-19 -0.13010214E-23 0.31529158E+03 -0.17522257E+02 [4]
Al g 0.26386461E+01 -0.33361981E-03 0.29072954E-06 -0.10687702E-09 0.14019385E-13 0.39560925E+05 0.48317142E+01 [4]
Al2 g 0.40327689E+01 0.31080371E-02 -0.26555275E-05 0.10139488E-08 -0.14265000E-12 0.57660543E+05 0.42808346E+01 [4]
Ga s 0.31516549E+01 0.47487811E-03 -0.13114719E-05 0.66957280E-09 -0.10309042E-12 0.31761301E+05 0.22722336E+01 [4]
Ga l 0.37332207E+01 -0.14576218E-02 0.12593146E-05 -0.45013529E-09 0.58809512E-13 -0.78157088E+03 -0.13777782E+02 [4]
Ga g 0.31516549E+01 0.47487811E-03 -0.13114719E-05 0.66957280E-09 -0.10309042E-12 0.31761301E+05 0.22722336E+01 [4]
In s 0.28708331E+01 0.50895697E-03 0.23897104E-05 0 0 -0.89967232E+3 -0.96810646E+01 [4]
In l 0.40047221E+01 -0.16093120E-02 0.12357138E-05 -0.40475261E-09 0.50565275E-13 -0.11326205E+04 -0.14615689E+02 [4]
In g 0.17106240E+01 0.27284880E-02 -0.15237756E-05 0.24935117E-09 -0.13543811E-14 0.28294009E+05 0.10393415E+02 [4]
Cl g 0.24863802E+01 0.85400259E-03 -0.10102948E-05 0.41513823E-090 -0.57351897E-13 0.13818230E+05 0.54745422E+01 [2]
Cl2 g 0.36723063E+01 0.19959920E-02 -0.17664869E-05 0.67118808E-09 -0.85427189E-13 -0.11692930E+04 0.53710238E+01 [2]
H g 0.24999969E+01 0.40554262E-16 -0.69589660E-19 0.36480813E-22 -0.59810677E-26 0.25473925E+05 -0.46019397E+00 [2]
H2 g 0.35835513E+01 -0.50820648E-03 0.80582475E-06 -0.26671703E-09 0.28964961E-13 -0.10611936E+04 -0.45955646E+01 [2]
N g 0.25022205E+01 -0.10929503E-04 0.17136711E-07 -0.10629382E-10 0.22781404E-14 0.56105014E+05 0.41705817E+01 [2]
N2 g 0.33489922E+01 0.22852471E-03 0.66433042E-06 -0.38603865E-09 0.60257282E-13 -0.10137940E+03 0.38564836E+01 [2]

Table 2s

 Thermodynamic properties of group-III hydrides (ChemKin format).
Component Phase a1 a2 a3 a4 a5 a6 a7 reference
AlH g 0.29920505E+01 0.19313058E-02 -0.89008762E-06 0.17659140E-09 -0.66198110E-14 0.28971460E+05 0.49959763E+01 [4]
AlH2 g 0.29899556E+01 0.49326258E-02 -0.25346247E-05 0.60656427E-09 -0.53207711E-13 0.28624960E+05 0.72437680E+01 [4]
AlH3 g 0.19873363E+01 0.11164632E-01 -0.65786378E-05 0.18095101E-08 -0.19009482E-12 0.23999886E+05 0.10457201E+02 [4]
GaH g 0.29623752E+01 0.21304955E-02 -0.11056997E-05 0.27502882E-09 -0.23505502E-13 0.24805959E+01 0.65474670E+01 [4]
GaH2 g 0.29812282E+01 0.55323277E-02 -0.31765828E-05 0.84445499E-09 -0.85359368E-13 0.30282972E+05 0.85657017E+01
GaH3 g 0.24500013E+01 0.10867555E-01 -0.66409192E-05 0.18952949E-08 -0.20627448E-12 0.15680233E+05 0.93830393E+01
InH g 0.29152219E+01 0.24766074E-02 -0.14984347E-05 0.44210391E-09 -0.47914809E-13 0.24856256E+05 0.76777967E+01 [4]
InH2 g 0.30615829E+01 0.60170750E-02 -0.38185434E-05 0.11155913E-08 -0.12315586E-12 0.35053547E+05 0.91236129E+01
InH3 g 0.29241131E+01 0.10796226E-01 -0.69214730E-05 0.20533707E-08 -0.23055240E-12 0.25887243E+05 0.79935951E+01

Table 3s

 Thermodynamic properties of group-III chlorides (ChemKin format).
Component Phase a1 a2 a3 a4 a5 a6 a7 reference
GaCl g 0.40828200E+01 0.10275066E-02 -0.82584758E-06 0.30159693E-09 -0.38982556E-13 -0.18930553E+05 0.53481325E+01 [4]
GaCl2 g 0.58256772E+01 0.27618590E-02 -0.24086603E-05 0.89405236E-09 -0.11624406E-12 -0.30854559E+05 0.22752045E+01 [4]
GaCl3 s 0.27254950E+01 0.29584829E-01 0 0 0 -0.65270941E+05 -0.82328905E+01 [4]
GaCl3 l 0.13109770E+02 0 0 0 0 -0.67257972E+05 -0.54894857E+02 [4]
GaCl3 g 0.81264039E+01 0.43397075E-02 -0.37045176E-05 0.13443762E-08 -0.17473299E-12 -0.54492248E+05 -0.83485211E+01 [4]
Ga2Cl6 g 0.17907141E+02 0.95219173E-02 -0.81418255E-05 0.29569337E-08 -0.38442017E-12 -0.12086372E+06 -0.44330387E+02 [4]

Table 4s

 Thermodynamic properties of group-III metal-organic compounds (ChemKin format).
Component Phase a1 a2 a3 a4 a5 a6 a7 reference
AlCH3 g 0.33152363E+01 0.10730808E-01 -0.53649153E-05 0.13219641E-08 -0.12963324E-12 0.69985773E+04 0.69088112E+01
Al(CH3)3 g 0.32762275E+01 0.38648068E-01 -0.21169742E-04 0.57086106E-08 -0.60677829E-12 -0.13086231E+05 0.12164379E+02
Al2(CH3)6 g 0.77694495E+01 0.81503404E-01 -0.45707472E-04 0.12565890E-07 -0.13556605E-11 -0.37792596E+05 -0.66613696E+01
GaCH3 g 0.25578342E+01 0.12336949E-01 -0.66536191E-05 0.17697148E-08 -0.18602651E-12 0.82459942E+04 0.11507155E+02
Ga(CH3)2 g 0.31015884E+01 0.24665912E-01 -0.13279303E-04 0.35247826E-08 -0.36978377E-12 0.74707731E+04 0.13886280E+02
Ga(CH3)3 g 0.19674198E+01 0.47163954E-01 -0.37019398E-04 0.17197050E-07 -0.34877739E-11 -0.78124671E+04 0.18869043E+02
InCH3 g 0.32606827E+01 0.10945619E-01 -0.56676425E-05 0.14649582E-08 -0.15127365E-12 0.24447299E+05 0.92182406E+01
In(CH3)3 g 0.43958263E+01 0.36932913E-01 -0.20120601E-04 0.54175515E-08 -0.57640580E-12 0.22113910E+05 0.89579139E+01

Table 5s

 Thermodynamic properties of compound species related to growth of group-III nitrides (ChemKin format). (*) Indexes s- and a- denotes the molecules C2H2 having different bond configurations: HC=CH and H2C=C respectively.
Component Phase a1 a2 a3 a4 a5 a6 a7 reference
CH g 0.36138827E+01 -0.82828147E-03 0.16896253E-05 -0.68730072E-09 0.89176108E-13 0.70792073E+05 0.15886242E+01 [3]
CH2 g 0.36456497E+01 0.95155874E-03 0.13138435E-05 -0.78153507E-09 0.11901737E-12 0.45817667E+05 0.23139800E+01 [3]
CH3 g 0.32140185E+01 0.49932545E-02 -0.10666071E-05 -0.94179151E-10 0.41825069E-13 0.16425353E+05 -0.32620959E+00 [3]
CH4 g 0.15216894E+01 0.94206100E-02 -0.20358736E-05 -0.16954382E-09 0.84231104E-13 -0.98265001E+04 0.11015042E+02 [3]
s-C2H2* g 0.32873503E+01 0.84711075E-02 -0.47845151E-05 0.14062688E-08 -0.16380579E-12 0.26033038E+05 0.30977851E+01 [3]
a-C2H2* g 0.37432140E+01 0.64649821E-02 -0.29878974E-05 0.67863179E-09 -0.61508807E-13 0.47452584E+05 0.36880757E+01
C2H4 g 0.51347290E+00 0.18255281E-01 -0.97529218E-05 0.25543735E-08 -0.26359173E-12 0.54190726E+04 0.18407655E+02 [3]
C2H5 g 0.41356879E+00 0.19656915E-01 -0.92762870E-05 0.20790714E-08 -0.17976542E-12 0.11950162E+05 0.22444201E+02 [3]
C2H6 g 0.14469981E+00 0.23658897E-01 -0.11545008E-04 0.27146353E-08 -0.24972355E-12 -0.11100895E+05 0.20160466E+02 [3]
HCl g 0.35477617E+01 -0.52495759E-03 0.12539209E-05 -0.55704126E-09 0.77853020E-13 -0.12146858E+05 0.23571698E+01 [2]
HN3 g 0.30696955E+01 0.91823215E-02 -0.55000486E-05 0.16008807E-08 -0.18008554E-12 0.34082455E+05 0.87750511E+01 [2]
NH4Cl s 0.15779218E+02 -0.32826760E-01 0.68126014E-04 -0.42994252E-07 0.91512370E-11 -0.41599526E+05 -0.71376421E+02 [5]
NH3 g 0.28571756E+01 0.49698173E-02 -0.10459846E-05 -0.59616310E-10 0.33876824E-13 -0.65887633E+04 0.54578631E+01 [2]
NH2 g 0.36485140E+01 0.99709004E-03 0.11450996E-05 -0.67166863E-09 0.10319335E-12 0.21710932E+05 0.23089927E+01 [2]
NH g 0.36081623E+01 -0.70482845E-03 0.13400834E-05 -0.56265529E-09 0.77335350E-13 0.39703545E+05 0.13808122E+01 [2]
N2H2 g 0.22848311E+01 0.65332679E-02 -0.10485018E-05 -0.26377069E-09 0.67449391E-13 0.24519210E+05 0.11328618E+02 [2]
N2H4 g 0.18125618E+01 0.16115998E-01 -0.90347623E-05 0.25420769E-08 -0.28283711E-12 0.10250740E+05 0.13915855E+02 [2]

Table 6s

 Thermodynamic properties of adducts related to growth of group-III nitrides (ChemKin format).
Component Phase a1 a2 a a4 a5 a6 a7 reference
Al·NH3 g 0.51515143E+01 0.58573417E-02 -0.16170505E-05 0.11451009E-09 0.12133096E-13 0.28286069E+05 -0.48274682E-01
(Al·N)3 g 0.45513774E+01 0.24224744E-01 -0.19583472E-04 0.68617042E-08 -0.87066457E-12 -0.65417224E+05 0.37152416E+01
MMA·NH g 0.53000416E+01 0.15817580E-01 -0.89597704E-05 0.25398503E-08 -0.28426358E-12 -0.19047211E+05 -0.38015130E-01
(MMA·NH)3 g 0.58446617E+01 0.78028253E-01 -0.51959593E-04 0.16480119E-07 -0.19828760E-11 -0.94988106E+05 0.64522837E+01
TMA·NH3 g 0.63159729E+01 0.46337132E-01 -0.24201379E-04 0.62752490E-08 -0.64727423E-12 -0.33328111E+05 -0.89507418E+00
(DMA·NH2)3 g 0.11133625E+02 0.12201319E+00 -0.75594693E-04 0.22848140E-07 -0.26665328E-11 -0.99526181E+05 -0.26267281E+02
Ga·NH3 g 0.50415777E+01 0.60423017E-02 -0.17099375E-05 0.13220508E-09 0.11191167E-13 0.22297756E+05 0.14946460E+01
(Ga·N)3 g 0.67417325E+01 0.20698420E-01 -0.17293197E-04 0.61883733E-08 -0.79656592E-12 -0.79656592E-12 -0.47959352E+01
MMG·NH g 0.54128110E+01 0.15466515E-01 -0.85993868E-05 0.23946771E-08 -0.26421186E-12 -0.14257212E+05 0.34268502E+00
(MMG·NH)3 g 0.78421436E+01 0.75178598E-01 -0.50082986E-04 0.15895148E-07 -0.19139941E-11 -0.67809637E+05 -0.17042245E+01
TMG·NH3 g 0.72199138E+01 0.43905101E-01 -0.21992163E-04 0.54490488E-08 -0.53816240E-12 -0.24366705E+05 -0.51898207E+01
(DMG·NH2)3 g 0.87149890E+01 0.12611576E+00 -0.78186312E-04 0.23569819E-07 -0.27410200E-11 -0.70701723E+05 -0.15101017E+02
(DMA·NH2)2(DMG·NH2) g 0.73936341E+01 0.13562588E+00 -0.92917003E-04 0.31735301E-07 -0.42292280E-11 -0.89258078E+05 -0.90006738E+01
(DMA·NH2) (DMG·NH2)2 g 0.97937059E+01 0.12425531E+00 -0.76968702E-04 0.23215922E-07 -0.27027562E-11 -0.79971211E+05 -0.20135984E+02
GaCl3·NH3 g 0.99445135E+01 0.14131038E-01 -0.81793973E-05 0.23593607E-08 -0.26734087E-12 -0.77974368E+05 -0.15271713E+02

Table 7s

 Thermodynamic properties of group-III nitrides (ChemKin format).
Component Phase a1 a2 a3 a4 a5 a6 a7 reference
AlN s 0.16484984E+00 0.16906333E-01 -0.19156391E-04 0.95997888E-08 -0.17389262E-11 -0.39016612E+05 -0.27932794E+01
AlN g 0.35951625E+01 0.12581327E-02 -0.17178569E-06 -0.42709248E-10 0.83346116E-14 0.51617150E+05 0.66104571E+01 [4]
GaN s 0.51341560E+00 0.18306308E-01 -0.21633569E-04 0.11081026E-07 -0.20603428E-11 -0.14507663E+05 -0.31255765E+01
GaN g 0.31180378E+01 0.28153203E-02 -0.22191154E-05 0.76417778E-09 -0.95775476E-13 0.25622984E+05 0.93780951E+01
InN s -0.17387340E+01 0.34314485E-01 -0.52155647E-04 0.35199074E-07 -0.87726745E-11 -0.91507858E+04 0.70544505E+01

Figure 1. Specific heat of solid AlN as a function of temperature (after reference [1] and reference [22]).

Figure 2. Total pressure (sum of Al and N2 partial pressures) measured during free evaporation of AlN in vacuum by torsion method [23]. For comparison the result of thermodynamic calculation of the total pressure is plotted in the figure.

Figure 3. Specific heat of solid GaN versus temperature [54] [55].

Figure 4. Total pressure (sum of Ga and N2 partial pressures) measured during free evaporation of GaN in vacuum by torsion-effusion method [62]. For comparison the result of thermodynamic calculation of the total pressure is plotted in the figure.

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