Characterization of AlGaN on GaN template grown by MOCVD

Abstract

ABSTRACT Al x Ga 1-x N layer was grown on sapphire substrate with GaN template by Metal Organic Chemical Vapor Deposition system (MOCVD). High temperature AlN (HT-AlN) interlayer was inserted between Al x Ga 1-x N layer and GaN template to solve the cracking problem that often appears on Al x Ga 1-x N surface when directly grown on high temperature GaN template. Optical microscope, scanning electron microscopy (SEM), atomic force microscope (AFM), high resolution x-ray diffraction (HRXRD) and cathodoluminescence (CL) were used for characterization. It was found that the cracking was successfully eliminated. Furthe rmore, the crystalline quality of Al x Ga 1-x N layer with HT-AlN interlayer was much improved. Interference fringes were found in the HRXRD images. CL test showed that yellow emission was much reduced for AlGaN layer w ith HT-AlN interlayer. Keywords: AlGaN, GaN template, AlN interlayer, MOCVD, crack, interference fringes 1. Introduction III-nitride materials which have wide band gap ranging from 3.43eV to 6.04eV are of great interest for many optoelectronic devices, such as blue and ultraviolet (UV) light emitting diodes (LEDs), laser diodes (LDs), and high temperature/high frequency transistors