Characterization of GaN/AlGaN epitaxial layers grown by metalorganic chemical vapour deposition for high electron mobility transistor applications

Abstract

GaN and AlGaN epitaxial layers are grown by a metalorganic chemical vapour deposition (MOCVD) system. The crystalline quality of these epitaxially grown layers is studied by different characterization techniques. PL measurements indicate band edge emission peak at 363.8 nm and 312 nm for GaN and AlGaN layers respectively. High resolution XRD (HRXRD) peaks show FWHM of 272 and 296 arcsec for the (0 0 0 2) plane of GaN and GaN in GaN/AlGaN respectively. For GaN buffer layer, the Hall mobility is 346 cm²/V-s and carrier concentration is 4.5 × 10¹⁶/cm³. AFM studies on GaN buffer layer show a dislocation density of 2 × 10⁸/cm² by wet etching in hot phosphoric acid. The refractive indices of GaN buffer layer on sapphire at 633 nm are 2.3544 and 2.1515 for TE and TM modes respectively.