Efficient acceptor activation in AlxGa1-xN/GaN doped superlattices

Mg-doped superlattices consisting of uniformly doped AlxGa1-xN and GaN laye rs are analyzed by Hall-effect measurements. Acceptor activation energies o f 70 meV and 58 meV are obtained for superlattice structures with an Al mol e 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 fr ee hole concentrations of 2 x 10(18) cm(-3) and 4 x 10(18) cm(-3) for x = 0 .10 and 0.20, respectively. The increase in hole concentration with Al cont ent of the superlattice is consistent with theory. The room temperature con ductivity measured for the superlattice structures are 0.27 S/cm and 0.64 S /cm for an At mole fraction of x = 0.10 and 0.20, respectively.