Investigation of Luminescence Spectra for InGaN/GaN Rectangular, Trapezoidal, and Triangular MQW Light-Emitting Diodes

In this paper, we present luminescence spectra for three types of light-emitting diodes (LEDs) with rectangular, trapezoidal and triangular InGaN/GaN multiple quantum wells (MQWs), analyzed under various bias conditions through extensive numerical analysis. The nature of luminescence spectra is analyzed on the light of energy band structure, electric field profile, carrier distribution in well and peak shifting of electron and hole concentrations. Our observation reports that the peak of emission spectra for trapezoidal QW (TQW) LED remains at the same wavelength under different bias conditions, unlike rectangular QW (RQW) and triangular QW (TNQW) LEDs. The shifting of luminescence peak towards the longer wavelength is only 1 nm for TQW LED, whereas 6 nm for RQW and 3 nm for TNQW LEDs when bias voltage changes from 0 to ±10 V. Moreover, the efficiency droop of TQW LED is very low and it is equal to 3.7%, in contrast of 27.8% for RQW and 7.4% for TNQW LEDs. Therefore, this high efficiency and color-stable lighting performance of TQW LED is useful for different photonic and optoelectronic applications.