Electrical properties of p-type GaN:Mg codoped with oxygen

Abstract
Codoping of p-type GaN with Mg and oxygen was investigated. By codoping with oxygen the hole concentrations increased to 2×1018cm−3 at 295 K, an order of magnitude greater than in Mg-doped epilayers. The resistivity of codoped layers decreased from 8 to 0.2 Ω cm upon oxygen codoping. Variable temperature Hall effect measurements indicated that the acceptor activation energy decreases from 170±5 meV in Mg-doped films to 135±5 meV upon oxygen doping. The higher hole concentration results in part from a decrease in the ionization energy of the acceptor.