Electrical and structural characterization of Mg-doped p-type Al0.69Ga0.31N films on SiC substrate

We report on the electrical and structural characterization of Mg-doped Al-rich p-type Al0.69Ga0.31N alloys on SiC substrate grown by metal organic chemical vapor deposition. The impact of growth conditions and dopant activation annealing conditions on the electrical conductivity was investigated. The most efficient activation was achieved by annealing in N2 gas at 1000°C for 3min in the presence of a SiO2 cap. The impact of p-GaN contact layer thickness was also studied. Higher growth temperature resulted in lower Mg incorporation, and for constant Mg concentration the resistivity increased with the increase in the growth temperature. Mg incorporation increased linearly with Mg effective flow. Transmission electron microscopy revealed the generation of vertical spike-like defects with increasing Mg doping. The resistivity also increased with the increase in Mg doping. A minimum resistivity of 10Ωcm was achieved at 670K.