Photoluminescence and photoluminescence excitation spectroscopy of in situ Er-doped and Er-implanted GaN films grown by hydride vapor phase epitaxy

Photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy have been carried out at 6K on the 1540 nm ⁴I _13/2 → ⁴I _15/2 emission of Er ³⁺ in in situ Er-doped and Er-implanted GaN grown by hydride vapor phase epitaxy (HVPE). The PL and PLE of these two different Er-doped HVPE-grown GaN films are compared with Er-implanted GaN grown by metal organic chemical vapor deposition (MOCVD). In the in situ Er-doped HVPE-grown GaN, the lineshape of the broad PLE absorption bands and the broad PL bands is similar to that in Er-doped glass. The PL spectra of this in situ Er-doped sample are independent of excitation wavelength, unlike the PL of the Er-implanted GaN. These PL spectra are quite different from the site-selective PL spectra observed in the Er-implanted GaN, indicating that the seven different Er ³⁺ sites existing in the Er-implanted MOCVD-grown GaN are not observed in the in situ Er-doped HVPE-grown GaN. Four of the seven different Er ³⁺ sites observed in the Er-implanted MOCVD-grown GaN annealed at 900°C under a flow of N ₂ are present in the Er-implanted HVPE-grown GaN annealed at 800°C in an NH ₃/H ₂ atmosphere.