Effects of growth pressure on the properties of p-GaN layers

The influence of growth pressure on the properties of p-GaN grown by metal-organic chemical vapor deposition method was investigated. The p-GaN layers were grown at low temperature under growth pressures ranging from 100 to 400 mbar. We find that higher growth pressure leads to lower Mg incorporation in the p-GaN layer and results in high resistivity of p-GaN grown at 400 mbar. By optimizing the Cp2Mg/TMGa ratio, however, low sheet resistivity can be achieved for p-GaN grown at 100–300 mbar. The p-GaN grown at 300 mbar using optimal Cp2Mg/TMGa ratio of 1.3% shows the highest hole concentration of 5.0×1017 cm−3 and the consequent minimum sheet resistivity of 2.6×104 Ω/sq. The superior electrical properties are ascribed to the reduction of compensation effect for the layer grown under the high growth pressure.

► We investigated growth pressure influence on the properties of p-GaN grown by MOCVD. ► Higher growth pressure leads to lower Mg incorporation in the p-GaN layer. ► Low sheet resistivity can be achieved for p-GaN grown at 100–300 mbar. ► Mg activation is more efficient for the 300 mbar-grown sample. ► Superior electrical properties are ascribed to the reduction of compensation effect.