The role of gaseous species in group-III nitride growth
S. Yu. Karpov
Advanced Technology Center
Yu. N. Makarov
Lehrstuhl für Strömungsmechanik, University of Erlangen-Nürnberg
M. S. Ramm
Ioffe Physical-Technical Institute
This article was received on Monday, June 30, 1997 and
accepted on Wednesday, October 15, 1997. Abstract
A quasi-thermodynamic model accounting for kinetics of
molecular nitrogen evaporation is applied to simulate the growth of binary and
ternary group-III nitrides using atomic group-III elements and molecular ammonia
as the sources. The values of the molecular nitrogen evaporation coefficients
from the surface of GaN and AlN necessary for the simulation are extracted from
experiments on free evaporation of the crystals in vacuum, while for InN only
estimates are available. The growth process of AlN and InN is studied by
analyzing the composition of the desorbed vapor species that are thought to
influence the native defect formation in group-III nitrides. Different channels
of desorption from the surfaces of group-III nitrides (related either to
group-III atoms or to their hydrides) are compared. Specific features of the
growth processes under the metal-rich and N-rich conditions are analyzed. The
developed approach is extended to study the growth of the ternary compounds GaInN and
AlGaN. The growth rate of ternary compounds versus temperature shows a two-drop
behavior corresponding to the rapid increase of the respective group-III atom
desorption. The effect is accompanied by a corresponding stepwise change in the
solid phase composition. Factors retarding the growth of ternary compounds --
the miscibility gap related to internal strain accumulated in the solid phase
due to the lattice mismatch of binary constituents, and the extra liquid phase
formation during growth -- are discussed with respect to GaInN.
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Cite this article as: MRS Internet J. Nitride Semicond. Res. 2, 45(1997).
last updated Saturday, July 24, 1999 6:21:55 PM.© 1997-1999 The Materials Research Society
