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 (σ_n) of the major nonradiative recombination centers (NRCs), namely, clusters of Ga vacancies (V_Gas) and N vacancies (V_Ns) such as (V_Ga)₃(V_N)₃, is estimated at a few times 10^-13 cm². This σ_n value is also comparable to that of the major NRCs in p-GaN:Mg epilayers, namely, V_Ga(V_N)₂ or V_Ga(V_N)₃, although the clustering sizes of the defects are different. These σ_n values are commonly larger than the hole capture-cross-section (σ_p = 7 × 10^-14 cm²) of the major NRCs, V_GaV_N divacancies, in n-type GaN.