MBE 法によるGaN 単結晶基板上へのⅢ族窒化物半導体のホモエピタキシャル成長

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GaN, AlGaN epilayers and GaN/Al0.15Ga0.85N multiple quantum wells (MQWs) were grown on GaN single crystals by molecular beam epitaxy. The crystalline quality of the GaN and AlGaN epilayers was investigated by X-ray diffraction and photoluminescence spectroscopy. The crystalline quality and surface flatness of epilayers on GaN(0001) single crystals were superior to those on GaN ) 1 000 ( single crystals. The homoepitaxial GaN layers on GaN ) 1 000 ( single crystals always showed higher residual carrier concentration and have a bad influence on intentional doping of Mg(p-dopant) and Si(n-dopant). Low temperature photoluminescence spectra of the GaN/Al0.15Ga0.85N MQW exhibited intense QW-related emission peaks. The variation of QW transition energy versus the well thickness (from 2 ML to 18 ML:1 ML=2.59Å) indicates the presence of built-in electric field in the wurtzite GaN/ Al0.15Ga0.85N heterostructure.