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

Abstract

Key words gallium nitride, hydrogen vapor phase epitaxy, metal organic vapor phase epitaxy, density functional theory. PACS 61.50.Ah, 81.10.AjRecent 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. Dedicated to Prof. Wolfgang Neumann on the occasion of his 65th birthday

Kinetic Monte Carlo simulations of GaN homoepitaxy on c- and m-plane surfaces

“…22 A number of density functional theory calculations for diffusion and reaction energies and barriers of Ga and N species including ammonia have been reported, providing insights into molecular mechanisms of the growth processes. [23][24][25][26][27][28] In general, KMC calculations can take advantage of parameter values based on such DFT results. However, in the absence of a complete set of reliable parameters for different GaN orientations, we have been using a more generic energy model that we relate to experimental studies.…”

Magnesium Double Nitride Mg3GaN3 as New Host Lattice for Eu2+ Doping: Synthesis, Structural Studies, Luminescence, and Band-Gap Determination

“…Gallium nitride has found broad application in high-perfor­mance light-emitting diodes (LEDs), because of its properties as a direct, wide band gap semiconductor. − Recently, crystal growth and doping of GaN have been studied thoroughly. − In contrast, investigations of the deriving ternary and higher nitridogallates or gallium nitrides have been scarcely pursued so far. Magnesium was found to be suited for p -doping in GaN or AlGaN thus increasing hole concentration. − Mostly, GaN:Mg has been synthesized by MOCVD with bis(cyclopentadienyl) magnesium (Cp 2 Mg) as the magnesium source. − The influence of such doping on the GaN lattice and its physical properties have been investigated in detail. − So-called “heavily doped GaN:Mg” was obtained when the magnesium concentration was ∼10 20 cm –3 and resulting photoluminescence bands at 2.8 eV (443 nm) and 3.2 eV (388 nm) were observed. ,− …”

Ba3Ga3N5—A Novel Host Lattice for Eu2+-Doped Luminescent Materials with Unexpected Nitridogallate Substructure

“…Gallium nitride GaN is a direct wide band gap semiconductor that has found increasing application in high performance light emitting diodes (LEDs). − While synthesis, crystal growth, and doping of GaN have been studied thoroughly, − the chemistry of ternary and higher nitridogallates deriving from binary GaN has been widely neglected as yet. In the literature, only a small number of ternary alkaline earth nitridogallates has been described, and thereof, only two compounds contain Ba. − Most nitridogallates are made up of GaN 4 tetrahedra which can be connected through both common corners and/or common edges. ,, Depending on the degree of condensation of the nitridogallate substructure, a broad range of structural motifs has been identified in nitridogallates, including one-dimensional chains of edge-sharing GaN 4 units (e.g., in Sr 3 Ga 2 N 4 ), two-dimensional sheets made up of Ga 2 N 6 units which are further linked through corners (e.g., in Ca 3 Ga 2 N 4 ), or three-dimensional networks built up from vertex- and corner-sharing tetrahedra (e.g., in Sr 3 Ga 3 N 5 ) .…”