Materials Research Society Symposium Proceedings 468, 105 (1997).
Below is the abstract submitted to the meeting, not the abstract of the published paper:
On the basis of band-theoretical investigation using the augmented spherical wave (ASW) method, we propose a valence control by a codoping method that is useful in experiments to obtain low-resistivity p-type GaN materials. P-type dopants, Be and Mg, eminently lead to a decrease in the absolute value of electrostatic energy with negative sign, which will shift N 2p levels towards higher energy regions. On the other hand, we find an increase in it for n-type GaN with doping of Si or O atoms. We propose a codoping method using donor dopants in a small controlled quantity for fabrication of low-resistivity p-type GaN materials. The codoping method that the donor dopants play an important role in increasing the absolute value of the electrostatic energy with negative sign of the materials will result in preventation of self-compensation due to native defects such as anions-vacancies. We verify that both GaN materials with codoping of 2Mg (Be) and Si ( O) are p-type conductivity and have large absolute value of the electrostatic energy with negative sign compared with that for GaN doped with 2 Mg (Be) atoms. From these findings in the model super-cells using our codoping methods, for the very low doping levels, we predict lower-resistivity p-type GaN with codoping of Si and 2Mg and p-type GaN codoped with O and 2Mg(Be) atoms with higher-concentrations. The practical codoping method would be more effective in material design for controlling the valence states of compounds having some of the nature of ionic chemical bonds.
This paper is part of Gallium Nitride and Related Materials II
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