Electrical and optical properties of p-type InGaN

Mg-doped InxGa1-xN alloys were grown by metal organic chemical vapor deposition on semi-insulating c-GaN/sapphire templates. Hall effect measurements showed that Mg-doped InxGa1-xN epilayers are p-type for x up to 0.35. Mg-acceptor levels (E-A) as a function of x, (x up to 0.35), were experimentally evaluated from the temperature dependent hole concentration. The observed E-A in Mg-doped In0.35Ga0.65N alloys was about 43 meV, which is roughly four times smaller than that in Mg doped GaN. A room temperature resistivity as low as 0.4 cm (with a hole concentration similar to 5x10(18) cm(-3) and hole mobility similar to 3 cm(2)/V s) was obtained in Mg-doped In0.22Ga0.78N. It was observed that the photoluminescence (PL) intensity associated with the Mg related emission line decreases exponentially with x. The Mg energy levels in InGaN alloys obtained from PL measurements are consistent with those obtained from Hall-effect measurements.