Influence of the TMAl source flow rate of the high temperature AlN buffer on the properties of GaN grown on Si(111) substrate

Abstract

GaN epilayers have been grown on Si(111) substrates with various high temperature AlN buffer layers by metal-organic chemical vapor deposition (MOCVD). It is found that, the surface morphology and structural and optical properties of the GaN epilayer strongly depends on the TMAl source flow rate. The properties of GaN films were characterized by X-ray diffraction, atomic force microscopy, Raman, photoluminescence and cathodoluminescence measurements. With the optimized TMAl source flow rate, we were able to obtain a 1-μm-thick crack-free GaN layer. The (0002) and (101¯2) XRD FWHM of the GaN film are 547 and 563 arcsec respectively, the tensile stress calculated from the Raman spectra is 0.4 GPa, and RMS roughness of AFM 5 μm × 5 μm scan is 0.539 nm.