Review: GaN growth by ammonia based methods - density functional theory study

Recent results in Density Functional Theory (DFT) simulations of ammonia-based growth of gallium nitride on GaN (0001) are reviewed. These simulations are important to the following GaN growth methods that use ammonia as active nitrogen source: ammonothermal, MOVPE, HVPE and also ammonia-source MBE. In the simulations of GaN growth, the two main approaches were discussed: (1) equilibrium, based on chemical potentials of the components, and (2) dynamic, based on consideration of atomistic processes on the surface. These two approaches are unified by the kinetic procedure of determination of the chemical potential levels for nitrogen and hydrogen as a function of partial pressure of ammonia. Here the DFT modeling of GaN(0001) surface employing the technique of the simulation of subsurface electric field is described and employed. The results of DFT modeling include the ammonia and molecular hydrogen adsorption on GaN(0001) surface that allows to determine some basic features of ammonia-based growth of GaN.