Investigations of Mg-doped GaN grown by metalorganic chemical vapor deposition

Electrical and optical properties of Mg-doped GaN films grown by metalorganic chemical vapor deposition are investigated as a function of the Cp ₂Mg flow rates through the Hall effect and photoluminescence measurements. It is found that there is a critical flow rate of Cp ₂Mg at which the hole concentration is maximum and the resistivity is minimum, simultaneously. The activation energy of shallow Mg acceptor is obtained about 160 meV from the temperature dependent Hall effect measurement. In case of high Mg incorporation, we found that Mg-related deep donors (E _d=540 meV) compensate the shallow acceptors. The strong blue emission around 2.72 eV of as-grown Mg-doped p-type GaN is sharply decreased after thermal annealing. This result indicates that the thermal annealing activates hydrogen passivated deep levels as well as Mg-H complexes.