Electrical characteristics of Mg-doped p-GaN treated with the electrochemical potentiostatic activation method

The electrical characteristics and carrier transport mechanism of Mg-doped p-GaN treated with the electrochemical potentiostatic activation (EPA) method was investigated. The EPA method resulted in lower H concentration up to 56% with a subsequent increase in hole concentration and improved ohmic contacts. The temperature-dependent electrical resistivity of the reference p-GaN followed a ∼T^-1/4 dependence, i.e., hopping conduction, while that of the EPA-treated sample began to follow a ∼T^-1 behavior involving band conduction. This was due to the reduced density of deep-level states associated with the Mg-H complex, e.g., from 1.28 × 10¹⁹ to ∼7.50 × 10¹⁸ cm^-3 after EPA treatment. The increase in the hole concentration was responsible for the enhanced ohmic contact via tunneling.