Photoexcited carrier recombination in wide m-plane InGaN/GaN quantum wells

Abstract

Carrier recombination in single 10 nm wide m-plane homoepitaxial In0.15Ga0.85N/GaN quantum wells was examined by time-resolved photoluminescence. The radiative recombination time at 3.5 K was found to be short, about 0.5 ns. This value and the single-exponential luminescence decay show that the localized exciton recombination is not affected by the in-plane electric field. At room temperature, the nonradiative recombination was prevalent. The data indicate that the nonradiative recombination proceeds via efficient recombination centers. Complexes of Ga vacancies with oxygen and/or related interface defects are suggested to play this role and thus provide a direction for future improvements in materials' quality.

Structural, electronic, and optical properties ofm-plane InGaN/GaN quantum wells: Insights from experiment and atomistic theory

“…This behavior is consistent with the experimental observation of single-exponential PL decay transients discussed in detail in Sec. IV B and observed experimentally by other groups [44,50]. Also the strong wave function overlap independent of the hole localization is consistent with the measured decay times being constant over the spectrum.…”

“…Second, the decay curves are nonexponential due to the variable in-plane separation of the separately localized electrons and holes [46,49]. Single-exponential decays in nonpolar QWs have also been reported by other groups [44,50]. The explanation proposed for the nature of the decay transients is that recombination involves localized excitons [44,50].…”

Comparative studies of efficiency droop in polar and non-polar InGaN quantum wells

“…In the case of the low excitation density measurements, the decay constant was largely independent of detection energy and had a value of 260 6 15 ps. This behaviour is consistent with the initial work of Marcinkevicius et al 2 and our previous measurements. 33 In all the previous work, the decay constants were assigned to be governed by radiative processes only so the similarity between our values of the decay constant and the work of others adds weight to our assumption that under the low injection conditions the efficiency of radiative recombination is 100%.…”

“…The samples were excited using the frequency tripled output of a 100 fs mode locked Ti:sapphire laser, with a photon energy of 4.881 eV. The use of a pulsed laser, with a pulse duration much shorter than the carrier recombination lifetimes for both samples, 2,8,34 ensures that the peak carrier concentration in the QWs is determined by the power density of the excitation source. This assumes that the light is mainly absorbed due to the excitation of carriers in the GaN and that these carriers are captured by the QWs.…”

Multimode scanning near-field photoluminescence spectroscopy and its application for studies of InGaN epitaxial layers and quantum wells

“…To avoid these drawbacks, nonpolar QWs with the c axis lying in the QW plane were proposed [25]. Indeed, in such QWs, even as wide as 10 nm, the radiative lifetimes are short, of the order of 1 ns [26]. Yet, the ideal picture of an m-plane QW, used in device simulations, does not take into account the band potential fluctuations and in-plane electric fields originating from the non-planarity of QW interfaces [27,28].…”