Doping and compensation in heavily Mg doped Al-rich AlGaN films

Record low resistivities of 10 and 30 omega cm and room-temperature free hole concentrations as high as 3 x 10(18) cm(-3) were achieved in bulk doping of Mg in Al0.6Ga0.4N films grown on AlN single crystalline wafer and sapphire. The highly conductive films exhibited a low ionization energy of 50 meV and impurity band conduction. Both high Mg concentration (> 2 x 10(19) cm(-3)) and low compensation were required to achieve impurity band conduction and high p-type conductivity. The formation of V-N-related compensators was actively suppressed by chemical potential control during the deposition process. This work overcomes previous limitations in p-type aluminum gallium nitride (p-AlGaN) and offers a technologically viable solution to high p-conductivity in AlGaN and AlN.