Effect of different substrates on material properties of cubic GaN thin films grown by LP-MOCVD method

Abstract

The III-nitride cubic phase are promising materials in photovoltaics and other optoelectronic devices due to their favorable material properties. This research work presents the growth of cubic gallium nitride (c-GaN) thin films on two different substrate gallium phosphide (GaP) and gallium arsenide (GaAs) substrates using the low-pressure metal–organic chemical vapor deposition (LP-MOCVD) technique. The growth conditions are modified for each substrate to obtain c-GaN epitaxial films with good crystalline quality. Stress values for c-GaN epitaxial layers 0.62 GPa and 1.24 GPa were calculated using X-ray diffraction measurements for c-GaN grown on GaP and GaAs substrates, respectively. The stress state calculated by XRD proved that in both cases, c-GaN on GaP and on GaAs substrates, they was compressed layers. Raman measurements showed two peaks for c-GaN at 555 cm−1 (TO) and 745 cm−1 (LO) modes for c-GaN grown on GaP. For GaAs, only observed 555 cm−1 (TO) mode. It obtained the formation of c-GaN epitaxial films on both substrates. The surface morphology and the quality of the films depend on the type of substrates, compact layers with better crystalline quality are observed in the samples grown in GaP than GaAs substrate. Band gap (Eg) of GaN was obtained with approximate values of 380 nm for c-GaN of both substrates, which is where the Eg of c-GaN is found.