Deep‐level luminescence at 1.93 eV in GaN prepared by ammonothermal growth

Abstract

Deep‐level luminescence at 1.93 eV (red luminescence) was observed from GaN grown by the acidic ammonothermal method. Typical deep emission at 2.2 eV (yellow luminescence) was not observed. The intensity decreased linearly with increasing temperature, which is different from the red and yellow luminescence reported thus far. The time decay of the luminescence appeared partially exponential, i.e. with the both possibilities of a simple two‐level transition and donor–acceptor pairs. The origin of the red luminescence is probably different from the previously reported one [J. Appl. Phys. 97, 061301 (2005)]. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Photoluminescence from (0 0 0 1) GaN grown by the acidic ammonothermal technique

“…1b. The 1.93 eV emission is clearly observed and is quite different from the spectra obtained from sample A and HVPE-GaN [8]. This type of emission was often observed from both the Ga and N-face.…”

“…Since GaN crystals fabricated by the ammonothermal technique have been produced only recently, evaluations on the crystal quality of ammonothermal GaN are therefore sparsely reported yet. Recently, in-depth evaluation using photoluminescence method has been reported [7,8]. The optical quality of the GaN grown by the ammonothermal method with acidic mineralizer is almost the same as those for the crystals grown by the hydrogen vapor phase epitaxy (HVPE) as shown by sample A in Fig.…”

“…The peak position decreases by almost 18 meV with the temperature rising from 10 to 150 K. The temperature dependence was different from that of the peaks near band edge. The decrease of band gap with increasing temperature was larger than that of the deep emission between 10 and 100 K. Time-resolved PL was performed in order to better investigate the origin of the observed RL [8]. The luminescence decay was non-exponential within 0.3 ms and was exponential after that.…”

Reviewing recent developments in the acid ammonothermal crystal growth of gallium nitride

“…PL measurements were made to evaluate the optical quality of some of the ammonothermal GaN samples and were recently presented in greater detail in Refs. [8,24,25]. A general observation by PL is that the GaN nucleated on the N-polar face seems of higher optical quality than the GaN nucleated on the Ga-polar face.…”

Optical characterization of bulk GaN substrates with c ‐, a ‐, and m ‐plane surfaces

“…The deep acceptor is again related to the V Ga -O N complex while for the deep donor a nitrogen vacancy-carbon-pair-defect (V N -C N ) is proposed. Recently, RL have been observed in GaN grown by an acidic ammonothermal method and attributed to the O contamination [9]. Analysis of the spectra in Fig.…”