(001) and (11n)n = 1,3 GaAs substrate orientations for growth of GaN layers by AP-MOVPE: impact of GaN buffer layer thickness

Abstract

The impact of GaN buffer layer thickness on the properties of GaN films grown by MOVPE on (001), (113), and (111) GaAs substrate orientations were investigated. GaN buffer layers with thickness of d_BL = 65 nm and d_BL = 130 nm were used in this study. The in situ characterization by Laser reflectometry technique show that the degradation of GaN samples surfaces as a function of growth time is larger for the growth with d_BL of 65 nm. The pre-deposition of d_BL = 130 nm can improve the thermal stability of the GaAs substrates. Patterned structures with cubic, pyramidal, columnar, and spherical shapes have been produced by the growth on the (hkl) GaAs substrate orientations with the two different d_BL at the growth temperature range of 700–850 °C. The average size of the GaN crystals increases by increasing d_BL from 65 to 130 nm. CL results show that the YL/NBE intensity ratio for samples grown with d_BL of 65 nm is approximately 1.5 and 2 times greater than the growth with d_BL of 130 nm. This is a synonym of the presence of a large density of defects in the GaN layers grown with d_BL of 65 nm.