Effect of Si doping in barriers of InGaN/GaN multiple quantum wells on the performance of green light-emitting diodes

Abstract

Green InGaN/GaN multiple quantum wells (MQWs) light-emitting diodes (LEDs) are of high In composition in well layers, a condition which results in large lattice mismatch between InGaN well layers and GaN barrier layers and hence boosts up the quantum-confined Stark effect (QCSE). Screening of the polarization electric fields within MQWs can effectively improve the internal quantum efficiency (IQE). This work investigates the effect of Si doping in barrier layers on the performance of green InGaN/GaN MQWs LEDs. It is revealed that a suitable doping density of Si (3.4 × 1016 cm−3) in barrier layers can promote the interfacial abruptness between the barrier and the well layers, reduce the In-composition fluctuation, and effectively screen the polarization electric fields. At the same time, suitable Si doping in barrier layers improves the lateral current spreading, alleviating the current crowding effect which is responsible for local heating and efficiency droop. However, overdoping of Si in barrier layers causes a series of negative effects, such as deteriorated interfacial quality and large current leakage. An effective approach for improving the performance of green LEDs is hence proposed.