The Properties of p-GaN with Different CpMg/Ga Ratios and Their Influence on Conductivity.

The effect of CpMg/Ga ratio on the properties of p-GaN was explored by scanning Hall probe, photoluminescence (PL), and atomic force microscopy measurement. It was found that p-GaN has an optimal doping concentration under 2% CpMg/Ga ratio, and higher or lower doping concentration is not beneficial to the conductivity. Hole concentration under the optimum condition is 4.2 × 10 cm at room temperature. If the CpMg/Ga ratio exceeds the optimum value of 2%, surface morphology and electrical conduction properties become poor, and blue emission at 440 nm, considered deep donor-to-acceptor pair transitions in the PL spectra, are dominant. The decrease in electrical properties indicates the existence of compensating donors because the hole concentration decreases at such high CpMg/Ga ratio. The obtained results indicate that Mg is not incorporated in the exact acceptor site under a heavy doping condition, but acts as a deep donor, instead. [ABSTRACT FROM AUTHOR]