Nucleation mechanism of GaN crystal growth on porous GaN/sapphire substrates

Abstract

Porous GaN/sapphire substrates have great application potential in the epitaxial growth of high-quality and low-stress GaN crystals. In this study, the growth behavior of epitaxially grown GaN on porous substrates was studied in detail for the first time in the nucleation stage. The results show that the porous structure induces the selective deposition of GaN at the initial stage, so that the GaN layer grown on the porous site cannot completely fill the pores, and many voids appear at the growth interface. Raman spectroscopy, high-resolution X-ray diffraction (HRXRD), and theoretical calculations can confirm that voids help reduce dislocations and relieve the stress of the growing GaN layer. This work has important reference value for understanding the growth of GaN crystals on porous substrates.