Tunable thermal quenching of photoluminescence in Mg-dopedp-type GaN

Abstract

We have studied the thermal quenching of the ultraviolet luminescence band with a maximum at about 3.25 eV in p-type Mg-doped GaN. The characteristic temperature of the thermal quenching of photoluminescence (PL) gradually shifted to higher temperatures with increasing excitation intensity. This effect is explained by a population inversion of charge carriers at low temperatures, which suddenly converts into a quasiequilibrium population as the temperature increases above the characteristic value. Tunable quenching of PL has been observed only in some of the GaN:Mg samples. The absence of the tunable quenching of PL in another group of GaN:Mg samples is preliminarily attributed to different types of dominant nonradiative defects in the two groups of samples.

Tunable thermal quenching of photoluminescence in GaN

“…The same can be said about the observed abrupt and tunable increase of the quantum efficiency of the UVL band with increasing excitation intensity. Such behavior is very similar to the behavior of the BL band in high-resistivity Zn-doped GaN [1,2] and the UVL band in p-type GaN:Mg [3]. We assume that, similar to the case of Mg-doped GaN [3], the abrupt and tunable quenching is caused by the thermal emission of holes from a shallow acceptor to the valence band, which triggers the sudden opening of some nonradiative channel of recombination.…”

“…Such behavior is very similar to the behavior of the BL band in high-resistivity Zn-doped GaN [1,2] and the UVL band in p-type GaN:Mg [3]. We assume that, similar to the case of Mg-doped GaN [3], the abrupt and tunable quenching is caused by the thermal emission of holes from a shallow acceptor to the valence band, which triggers the sudden opening of some nonradiative channel of recombination. This phenomenon can be quantitatively explained with a phenomenological model involving a shallow donor, a shallow acceptor and an unknown nonradiative defect (deep donor).…”

“…The "activation energy" of this abrupt thermal quenching of PL and the capture characteristics for the defect causing the PL would be physically unreasonable if the quenching was explained by any of the traditional models. Another unusual feature was that the characteristic temperature of the abrupt thermal quenching, T 0 , strongly depended on the excitation intensity and can be tuned between 130 and 230 K. Similar behavior of PL has been observed for the ultraviolet luminescence (UVL) band in p-type GaN:Mg [3]. The unusual PL behavior has been attributed to a sudden redirection of the carrier recombination flow from a radiative channel (responsible for the observed PL) to a nonradiative channel.…”

“…1 Introduction Recently, we reported the observation of abrupt and tunable thermal quenching of photoluminescence (PL) in Zn-doped and Mg-doped GaN [1][2][3]. For high-resistivity GaN:Zn, the intensity of the blue luminescence (BL) band dropped by more than two orders of magnitude within a few Kelvins [1,2].…”

Carrier-capture characteristics of point defects in GaN and ZnO

“…Moreover, the OL band is commonly observed in ZnO grown by the hydrothermal (HT) method, and the samples have high resistivity. Then, we may expect that the thermal quenching is abrupt (but smoothed due to certain reasons) and does not reveal any activation energy, similar to the case of high-resistivity GaN doped with Zn or Mg [14,31]. In this case, Eq.…”