Si Doping of GaN in Hydride Vapor-Phase Epitaxy

Abstract

Growth of GaN boules by hydride vapor-phase epitaxy (HVPE) is very attractive for fabrication of GaN substrates. Use of dichlorosilane as a source for Si doping of bulk GaN is investigated. It is shown that no tensile strain is incorporated into mm-thick, Si-doped GaN layers on sapphire substrates if the threading dislocation density is previously reduced to 2.5 × 107 cm−2 or below. High-quality GaN layers with electron densities up to 1.5 × 1019 cm−3 have been achieved, and an upper limit of about 4 × 1019 cm−3 for Si doping of GaN boules was deduced considering the evolution of dislocations with thickness. A 2-inch, Si-doped GaN crystal with length exceeding 6 mm and targeted Si doping of about 1 × 1018 cm−3 is demonstrated.