Characterization of lightly-doped n- and p-type homoepitaxial GaN on free-standing substrates

Abstract

Hall-effect measurements for n-type and p-type GaN with low doping concentration are presented. The GaN layers were grown by metal-organic vapor phase epitaxy on hydride-vapor-phase-epitaxy-grown free-standing GaN substrates. For n-GaN, the origin of acceptor which compensating donor is not only C but also native defects for the Si doping concentration of 1016 cm−3 level. The electron mobility is mainly limited by ionized impurity scattering or polar optical phonon scattering in the temperature less or higher than 200 K, respectively. For p-GaN, lightly Mg doping of mid 1016 cm−3 was achieved, which shows the donor concentration of 3.2×1016 cm−3 and the mobility of 31 cm2/Vs at 300 K.