Dynamics of carrier recombination and localization in AlGaN quantum wells studied by time-resolved transmission spectroscopy

Abstract

Time-resolved transmission and photoluminescence measurements were performed on Al0.35Ga0.65N/Al0.49Ga0.51N quantum well structures with different well widths. Comparison of transmission and luminescence data shows that dynamics of electrons and holes excited into extended quantum well states are governed by nonradiative recombination. For excita-tion into potential minima formed by band gap fluctuations, localization of electrons was observed. Excitation energy dependence of the pump-probe transient shape allows estimating locali-zation potential, which is about 80 meV independently of the well width, and is prob-ably caused by fluctuations of AlN molar fraction.

Photoluminescence Study of Carrier Localization and Recombination in Nearly Strain‐Balanced Nonpolar InGaN/AlGaN Quantum Wells

“…[44] C-plane QWs were found to have even larger average localization depths, as large as 80 meV. [45] The small localization depth of our undoped heterostructures is a direct consequence of our PL lines being narrower than previously reported in the literature for the G, [19] and b) doped sample H. The data in panel (a) was reproduced from Ref. [19] with permission of AIP Publishing.…”

“…[ 44 ] C‐plane QWs were found to have even larger average localization depths, as large as 80 meV. [ 45 ] The small localization depth of our undoped heterostructures is a direct consequence of our PL lines being narrower than previously reported in the literature for the m‐plane InGaN/GaN QWs, [ 8,22,46,47 ] and is likely due to very different growth conditions employed by PAMBE as compared to previous reports that employed MOCVD.…”

Impacts of Si-doping on vacancy complex formation and their influences on deep ultraviolet luminescence dynamics in AlxGa1−xN films and multiple quantum wells grown by metalorganic vapor phase epitaxy

“…Due to the limited availability of desirable femtosecond excitation sources operated at DUV wavelengths, only several papers have dealt with the emission dynamics of (Al,Ga)N in the UV-C range. 21,48,67,[95][96][97][98][99][100][101][102][103][104] The authors have been studying the recombination dynamics of excitons and/or free carriers in UID AlN and Al x Ga 1−x N alloys using TRPL 96) and time-resolved cathodoluminescence (TRCL) measurements. 91,97,98) For the TRPL measurement, approximately 200 fs pulses of a frequency-quadrupled ( w 4 ) mode-locked Al 2 O 3 :Ti laser were used as the excitation source.…”

“…Accordingly, direct measurement of t minority and spatially resolved luminescence measurement should be carried out on the AlGaN wells. However, because of the limited availability of femtosecond pulsed lasers applicable at DUV wavelengths, few groups have dealt with 21,48,67,[95][96][97][98][99][100][101][102][103][104] the emission dynamics of WBG AlN and Al x Ga 1−x N alloys of high x. Nonetheless, the importance of localization and delocalization of excitons has been discussed for DUV light-emitting Al x Ga 1−x N QWs.…”

“…Nonetheless, the importance of localization and delocalization of excitons has been discussed for DUV light-emitting Al x Ga 1−x N QWs. 98,[100][101][102][103] Lefebvre et al 102) and Scajev et al 103) have discussed the luminescence dynamics of localized excitons in Al x Ga 1−x N/Al y Ga 1−y N MQWs grown by the same group of Refs.86 and 93, by changing the measuring temperature and excitation power. However, either the atomistic origin of NRCs or Si-doping effects has not been assessed.…”