Temperature‐dependent emission shift and carrier dynamics in deep ultraviolet AlGaN/AlGaN quantum wells

Abstract

Radiative and nonradiative processes in deep ultraviolet (DUV) AlGaN/AlGaN multiple quantum wells (MQWs) grown by LP‐MOCVD have been studied by means of deep ultraviolet time‐integrated photoluminescence (PL) and time‐resolved photoluminescence (TRPL) spectroscopy. As the temperature is increased, the peak energy of DUV‐AlGaN/AlGaN MQWs PL emission (Ep) exhibits a similarly anti‐S‐shaped behavior (blueshift – accelerated redshift – decelerated redshift): Ep increases in the temperature range of 5.9–20 K and decreases for 20–300 K, involving an accelerated redshift for 20–150 K and an opposite decelerated redshift for 150–300 K with temperature increase. Especially at high temperature as 300 K, the slope of the Ep redshift tends towards zero. This temperature‐induced PL shift is strongly affected by the change in carrier dynamics with increasing temperature. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

AlxGa1−xN‐Based Quantum Wells Fabricated on Macrosteps Effectively Suppressing Nonradiative Recombination

“…Figure plots the reported RT PL lifetimes as a function of the emission wavelength. It should be noted that as pointed out in multiple papers, the dominant recombination process at RT is nonradiative recombination, which is also true for our samples within our experimental condition. Therefore, Figure shows a trend of nonradiative recombination lifetimes.…”

“…In contrast, the RT PL lifetime of Al x Ga 1− x N QWs is 1.8 ns at a wavelength of 275 nm and becomes shorter as the emission wavelength decreases. A typical PL lifetime for Al x Ga 1− x N QWs emitting at a sub‐250 nm wavelength is a few hundred ps, as described in detail below . That is, increasing the Al composition shortens the lifetime, which is most likely due to the higher point‐defect densities in Al‐rich Al x Ga 1− x N.…”

Picosecond-laser-excited photoluminescence study of AlGaN quantum wells on epitaxially laterally overgrown AlN/sapphire under selective and non-selective excitation conditions

“…Consequently, the PL efficiency is not a good measure of the RRE under non-selective excitation conditions. Figure 5(e) shows the TRPL decay under selective excitation conditions at 6 and 293 K. The PL lifetime at 293 K is longer than that at 6 K. Contrary to the results of previous studies, [26][27][28] this result indicates that radiative recombination processes in the QW layers are efficient at RT. 29) In general, radiative and non-radiative recombination lifetimes become longer and shorter, respectively, with increasing temperature.…”

Optical properties of magnesium doped AlxGa1−xN (0.61 ≤ x ≤ 0.73)

“…5 A thin AlN buffer layer of about 80 nm thickness grown at 600 8C was used to initiate the growth. A 1 lm AlN layer grown at 1200 8C was used as high temperature template followed by a 1.2 lm thick Mg-doped AlGaN layer grown under 1000 8C.…”