Polarization of edge emission from III-nitride light emitting diodes of emission wavelength from 395to455nm

Polarization-resolved edge-emitting electroluminescence of InGaN∕GaN multiple quantum well (MQW) light emitting diodes (LEDs) from 395to455nm was measured. Polarization ratio decreased from 3.2 of near-ultraviolet LEDs (395nm) to 1.9 of blue LEDs (455nm). Based on TE mode dominant emissions in InGaN∕GaN MQWs, compressive strain in well region favors TE mode, indium induced quantum-dot-like behavior leads to an increased TM component. As wavelength increased, indium enhanced quantum-dot-like behavior became obvious and E‖C electroluminescence signal increased thus lower polarization ratio. Electroluminescence spectrum shifts confirmed that quantum dotlike behaviors rather than strain might be dominant in modifying luminescence mode of InGaN∕GaN MQWs from near ultraviolet to blue.