Thermal Annealing Effects on P-Type Mg-Doped GaN Films

Low-resistivity p-type GaN films were obtained by N₂-ambient thermal annealing at temperatures above 700°C for the first time. Before thermal annealing, the resistivity of Mg-doped GaN films was approximately 1×10⁶ Ω·cm. After thermal annealing at temperatures above 700°C, the resistivity, hole carrier concentration and hole mobility became 2 Ω·cm, 3×10¹⁷/cm³ and 10 cm²/V·s, respectively. In photoluminescence measurements, the intensity of 750-nm deep-level emissions (DL emissions) sharply decreased upon thermal annealing at temperatures above 700°C, as did the change in resistivity, and 450-nm blue emissions showed maximum intensity at approximately 700°C of thermal annealing.