Quality-enhanced GaN epitaxial films on Si(111) substrates by in situ deposition of SiN on a three-dimensional GaN template

Abstract

High-quality crack-free GaN epitaxial films were successfully grown on Si(111) substrates using metal–organic chemical vapor deposition by in situ depositing SiN on a 3-dimensional (3D) GaN template. The GaN epitaxial films with 0–600 s 3D GaN templates were grown. It was found that the crystalline quality of GaN epitaxial films could be optimized and the cracks could be suppressed within the window of the growth time of the 3D GaN template between 0 to 600 s. For the sample with 180 s 3D GaN template, X-ray rocking curve measurements revealed the minimum full-width at half-maximum values of 348 and 406 arcsec for GaN(0002) and GaN(10−12), respectively, indicating the best crystalline quality among all the samples. Furthermore, scanning electron microscopy and in situ reflectance curves suggested that the 3D GaN template growth time changed the size and density of the GaN islands on the 3D GaN template surface, thus affecting the subsequent coalescence process of GaN islands after SiN deposition, and consequently resulted in variation in the crystalline quality and the stress of GaN epitaxial films. This work broadens the approach to achieve high-quality crack-free GaN epitaxial films on Si substrates for applications in GaN-based devices.