Room-temperature photoluminescence lifetime for the near-band-edge emission of (000 1 ¯ ) p-type GaN fabricated by sequential ion-implantation of Mg and H

Photoluminescence (PL) spectra of (000 1 ¯ ) N-polar p-type GaN fabricated by using the sequential ion-implantation of Mg and H with subsequent high temperature annealing exhibited the near-band-edge (NBE) emission at 300 K. The longest PL lifetime ( τ PL ) for the NBE emission of the sample with Mg and H concentrations of 1 × 1019 and 2 × 1020 cm−3, respectively, annealed at 1230 °C was 18 ps at 300 K. This value is almost comparable to that of the (0001) Ga-polar p-type Mg-doped GaN (p-GaN:Mg) homoepitaxial film of the same Mg concentration. By correlating τ PL and the concentration of major vacancy-type defects quantified using positron annihilation spectroscopy, the electron capture-cross-section (σn) of the major nonradiative recombination centers (NRCs), namely, clusters of Ga vacancies (VGas) and N vacancies (VNs) such as (VGa)3(VN)3, is estimated at a few times 10−13 cm2. This σn value is also comparable to that of the major NRCs in p-GaN:Mg epilayers, namely, VGa(VN)2 or VGa(VN)3, although the clustering sizes of the defects are different. These σn values are commonly larger than the hole capture-cross-section (σp = 7 × 10−14 cm2) of the major NRCs, VGaVN divacancies, in n-type GaN.