Extremely Slow Decay of Yellow Luminescence in Be‐Doped GaN and Its Identification

Abstract

The extremely slowly decaying yellow luminescence band around 2.08 eV in GaN:Be:O is studied by continuous-wave and time-resolved photoluminescence, as well as photoluminescence excitation spectroscopy and absorption. The lifetime obtained for this process is around 2.2 s and is thermally quenched for temperatures between 250 and 400 K. From the photoluminescence excitation measurements, two major pumping thresholds at around 2.7 and 3.1 eV can be identified. We discuss the origin of the Be-related 2.08 eV transition as well as the origin of the overlaying photoluminescence bands at 1.88 and 2.12 eV.

Photoluminescence from Be‐Doped GaN Grown by Metal‐Organic Chemical Vapor Deposition

“…[ 40,41 ] These facts indicate that the transition level of the defect responsible for the YL Be2 band is not lower than ≈0.8 eV above the valence band. Moreover, from analysis of time‐resolved PL and PL excitation spectra, Lamprecht et al [ 40 ] concluded that the broad YL Be2 band consists of three PL bands with maxima at 1.88, 2.08, and 2.12 eV, one of which (2.12 eV) is likely caused by the C N acceptor. The 2.08 eV component was attributed to the Be Ga O N complex.…”

“…The decay of the YL Be2 intensity after a pulsed excitation is extremely slow (up to several seconds at low temperatures). [40] Most importantly, the quenching of the YL Be2 band begins at temperatures well above room temperature, and the YL Be2 band could be excited with photon energies as low as 2.75 eV. [40,41] These facts indicate that the transition level of the defect responsible for the YL Be2 band is not lower than %0.8 eV above the valence band.…”

“…[40] Most importantly, the quenching of the YL Be2 band begins at temperatures well above room temperature, and the YL Be2 band could be excited with photon energies as low as 2.75 eV. [40,41] These facts indicate that the transition level of the defect responsible for the YL Be2 band is not lower than %0.8 eV above the valence band. Moreover, from analysis of time-resolved PL and PL excitation spectra, Lamprecht et al [40] concluded that the broad YL Be2 band consists of three PL bands with maxima at 1.88, 2.08, and 2.12 eV, one of which (2.12 eV) is likely caused by the C N acceptor.…”

“…The 2.08 eV component was attributed to the Be Ga O N complex. [14,40] Note that the HNPS-grown GaN samples contain a very high concentration of oxygen (%3 Â 10 19 cm À3 ). The 0/þ level of the Be Ga O N complex is calculated at 0.26 eV above the valence band, and the PL band maximum is predicted at 2.02 eV.…”

Photoluminescence from defects in GaN

“…39 A similar yellow band in bulk GaN with high concentrations of Be and O is attributed to the BeGaON complex. 40 This yellow band is quenched only at T > 500 K, 41 which indicates that the related defect level is located at about 0.8 eV above the VBM. The third mechanism of PL quenching is the Seitz-Mott mechanism.…”