Observation of localized centers with anomalous behavior in light-emitting heterostructures with multiple InGaN/GaN quantum wells

For the first time, using a complex of admittance spectroscopy, light-emitting heterostructures with InGaN/GaN multiple quantum wells were studied in a wide temperature range of 6–300 K. Three peaks are found in the conductance spectra; these peaks correspond to emission of charge carriers from the quantum wells and point defects distributed in the semiconductor bulk. Two low-temperature peaks possess an anomalous behavior, specifically, the peak with a low value of apparent activation energy (17 meV) is shifted to higher temperatures compared with the higher-energy peak (30 meV). The latter is attributed to a bulk defect having anomalously large capture cross section σ n = 1.5 × 10−11 cm2.