Non-linear Surface Reaction Kinetics In Gaas Selective Area Movpe

摘要

Two-dimensional numerical simulation on growth rate non-uniformity of selective area growth (SAG) in metal-organic vapor phase epitaxy (MOVPE) is an effective method to examine the surface reaction kinetics, which is difficult to be investigated in mass-transport limited growth regime. Non-linear kinetic analysis based on the Langmuir-Hinshelwood mechanism is revealing the intrinsic process in MOVPE. Two important kinetic parameters, surface reaction rate constant (k_s~n) and adsorption equilibrium coefficient (K), were successfully extracted from GaAs SAG-MOVPE on (100) exact and 2° off misoriented substrates in the temperature range of 520-600℃. The activation energy is 126-127 kJ/mol for k_s~n, and -53 to -59 kJ/mol for K. The surface coverage of Ga-species during the GaAs growth can be estimated from these kinetic parameters as 0.05-0.60. There is a critical temperature (T_c) for the conversion of GaAs surface reaction mode. When growth temperature is higher than T_c, nonlinear kinetic can be simplified as linear kinetic mode which is easier in calculation. T_c was found to be 600℃ for (100) exact GaAs substrate and 650 ℃ for 2° off substrate.