Efficient acceptor activation in AlxGa1-xN/GaN doped superlattices

Abstract

Mg-doped superlattices consisting of uniformly doped AlxGa 1-xN and GaN layers are analyzed by Hall-effect measurements. Acceptor activation energies of 70 meV and 58 meV are obtained for super-lattice structures with an Al mole fraction of x = 0.10 and 0.20 in the barrier layers, respectively. These energies are significantly lower than the activation energy measured for Mg-doped GaN thin films. At room temperature, the doped superlattices have free hole concentrations of 2 × 1018 cm -3 and 4 × 1018 cm-3 for x = 0.10 and 0.20, respectively. The increase in hole concentration with Al content of the superlattice is consistent with theory. The room temperature conductivity measured for the superlattice structures are 0.27 S/cm and 0.64 S/cm for an Al mole fraction of x = 0.10 and 0.20, respectively.