Depth Analyses of Acceptor and Compensating Donor Concentrations in Mg‐Ion‐Implanted GaN with Ultra‐High‐Pressure Annealing

Depth analyses of acceptor concentration ( N a ) and compensating donor concentration ( N d ) are presented for Mg‐ion‐implanted GaN after ultra‐high‐pressure annealing (UHPA). The UHPA processes are carried out at 1300 °C under 500 MPa of nitrogen for various annealing durations. Photoluminescence measurements combined with stepwise etching reveal the depth dependence of N a in both the Mg‐ion‐implanted region and the diffusion region where Mg atoms diffuse deeply during UHPA. In the early stage of UHPA (5 min), N a in the implanted region is approximately one‐tenth that of the Mg concentration ([Mg]), whereas N a in the diffusion region is close to [Mg], indicating that the Mg activation in the implanted region requires a longer UHPA duration than that in the diffusion region. N a and N d in the implanted region are estimated from Hall‐effect measurements and a step etching. N a after 15 min UHPA reaches sufficiently high level ( N a ≈ [Mg]); however, N d remains high ( N d / N a ≈ 50%) and diminishes with the prolongation of UHPA duration (60 min), reaching a low level ( N d / N a ≈ 20%). These findings indicate that the required UHPA duration is determined by the time needed to achieve a significant reduction in N d within the implanted region.