TY - JOUR
T1 - Thermodynamic and kinetic approach in density functional theory studies of microscopic structure of GaN(0001) surface in ammonia-rich conditions
AU - Krukowski, Stanisaw
AU - Kempisty, Pawe
AU - Jalbout, Abraham F.
N1 - Funding Information:
The calculations reported in this paper were performed using computing facilities of the Interdisciplinary Centre for Modelling (ICM) of Warsaw University. The research published in the paper was supported by Poland’s Ministry of Science and Informatics Grants Nos. R02 036 01 and N202 042 32/1171.
PY - 2008
Y1 - 2008
N2 - GaN (0001) surface in an ammonia-rich vapor ambient, typical for ammonia annealing, metalo-organic vapor phase epitaxy (MOVPE) or hydride vapor phase epitaxy (HVPE) was considered. It was shown that, in these three cases, the stationary state of the surface corresponds to condition far from equilibrium. The chemical potential of nitrogen and hydrogen at the surface was determined using kinetic arguments, i.e., derived form the magnitude of flux of ammonia. For HVPE and MOVPE growth, the chemical potential of gallium depends on the distance from the steps. Thus, only far distance from the step value of the gallium chemical potential at the GaN(0001) surface could be determined in similar way. In the alternative case of GaN annealing in ammonia atmosphere, gallium chemical potential at the surface remains undetermined (the surface is in a metastable state). Additionally, using thermodynamic arguments, the limits for the chemical potential of gallium (upper) and nitrogen (lower) were formulated for the case of vapor growth, and expressed as functions of temperature and pressure. The results, regarding the atomic processes on the GaN(0001) surface, were obtained using the SIESTA, density functional theory based code, and consequently employed in the comparable thermodynamic and kinetic analysis of the state of GaN(0001) surface.
AB - GaN (0001) surface in an ammonia-rich vapor ambient, typical for ammonia annealing, metalo-organic vapor phase epitaxy (MOVPE) or hydride vapor phase epitaxy (HVPE) was considered. It was shown that, in these three cases, the stationary state of the surface corresponds to condition far from equilibrium. The chemical potential of nitrogen and hydrogen at the surface was determined using kinetic arguments, i.e., derived form the magnitude of flux of ammonia. For HVPE and MOVPE growth, the chemical potential of gallium depends on the distance from the steps. Thus, only far distance from the step value of the gallium chemical potential at the GaN(0001) surface could be determined in similar way. In the alternative case of GaN annealing in ammonia atmosphere, gallium chemical potential at the surface remains undetermined (the surface is in a metastable state). Additionally, using thermodynamic arguments, the limits for the chemical potential of gallium (upper) and nitrogen (lower) were formulated for the case of vapor growth, and expressed as functions of temperature and pressure. The results, regarding the atomic processes on the GaN(0001) surface, were obtained using the SIESTA, density functional theory based code, and consequently employed in the comparable thermodynamic and kinetic analysis of the state of GaN(0001) surface.
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U2 - 10.1063/1.3037218
DO - 10.1063/1.3037218
M3 - Article
C2 - 19102550
AN - SCOPUS:57849138312
VL - 129
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
SN - 0021-9606
IS - 23
M1 - 234705
ER -