The effect of carrier localization in InGaN/GaN multiple quantum wells (MQWs) light-emitting diodes is investigated by photoluminescence (PL) and time-resolved PL (TRPL) measurements. PL results show that two peaks obtained by Gaussian fitting both relate to the emission from localized states. By fitting the TRPL lifetimes at various emission energies, two localization depths corresponding to the In-rich regions and quasi-MQWs regions are obtained. Using a model we proposed, we suggest that compositional fluctuations of In content and variation of well width are responsible for carrier localization in In-rich regions and quasi-MQWs regions, respectively.
Photoreflectance spectroscopy is utilized to study the effect of dilute nitrogen and antimony on the electronic band structure of as-grown GaAs1-x-ySbxNy alloys, which are potential materials for 1 eV solar cells and long-wavelength optoelectronic devices. The band gap, spin–orbit splitting, and valence-band maximum to the N-induced upward conduction-band transition, for the first time, are obtained and analyzed using the double-band anticrossing model. The EN level with respect to the GaAs valence-band maximum and the interaction potential are determined as 1.540 and 2.839 eV, respectively. The results are helpful information for intermediate-band solar cell application.
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