Development of new substrate technologies for GaN LEDs: atomic layer deposition transition layers on silicon and ZnO

Abstract

Al₂O₃ layers have been deposited by atomic layer deposition (ALD) on both silicon and zinc oxide (ZnO) substrates as a transition layer for MOCVD growth of GaN. These Al2O3 layers have been shown to reduce tensile strain and cracking in GaN thin films on Si, and they have also been shown to help suppress impurity diffusion from the ZnO substrate into the GaN layers. Surface morphology of the ALD-grown layers was investigated using scanning electron microscopy (SEM), and structural properties were studied using high resolution x-ray diffraction (HR-XRD). GaN thin films were then grown on these layers to determine the effects of the Al₂O₃ layer on subsequent GaN quality. The optical and structural properties of these films were studied, as well as surface morphology. GaN layers grown using the Al₂O₃ layers on Si in particular exhibit structural and optical properties approaching those of typical GaN thin films on sapphire, which shows significant promise for high performance GaN-based devices on Si substrates.