Redistribution of carrier localization in InGaN-based light-emitting diodes for alleviating efficiency droop

Abstract

We propose an efficient method for reducing efficiency droop in InGaN QWs by redistributing carrier localization via thermal annealing, which results in increased internal quantum efficiency (IQE) in this study. Entire structures of InGaN-based light-emitting diode (LED) were grown using metal-organic chemical vapor deposition. After thermal annealing, the photoluminescence (PL) intensity of the InGaN LED was gradually increased up to 900 °C, as confirmed by room-temperature macro-PL spectroscopy. The temperature-dependent PL spectra indicated that the In-rich InGaN cluster's local energy band was flattened by the thermal annealing treatment. Moreover, excitation power-dependent PL spectroscopy confirmed that redistribution of carrier localization in InGaN QWs alleviated the efficiency droop phenomenon. Furthermore, the flattened local energy band of the In-rich InGaN cluster and the increased carrier localization site implied improved IQE.