Abstract
Two InGaN/GaN multiple quantum well (MQW)-based blue light emitting diodes (LEDs) emitting photons at approximately the same wavelength, with different indium contents and well widths, are prepared, and the temperature-dependences of their electroluminescence (EL) spectra at different fixed injection currents are investigated. The results show that, compared with sample B with its lower indium content and larger well width, sample A with its higher indium content and smaller well width, has a stronger carrier localization effect and higher external quantum efficiency (EQE) at the lower fixed currents; however, upon increasing the injection current, both the localization effect and EQE for sample A decrease at a faster rate. The former is mainly attributed to the deeper potential levels due to the larger indium fluctuations originating from the higher indium content, and to the smaller well width-induced stronger carrier quantum-confine effect (QCE); the latter is mainly attributed to the more significant growing in the electron leakage and/or electron overflow originating from the smaller well width and larger lattice mismatch-induced stronger piezoelectric field, and to the more significant reduction in carrier localization effect originating from the smaller well width-induced smaller density of high-energy localized states.
Highlights
InGaN/GaN multiple quantum wells (MQWs) acting as active layers in light emitting diodes (LEDs) and laser diodes (LDs) have attracted significant attention, since by tuning the indium composition in an InGaN well layer, the whole spectral range, corresponding to near-infrared to visible and up to near-ultraviolet emissions, can be covered by the nitride system[1,2,3,4]
To produce a high-efficiency blue LED, two InGaN/GaN MQW-based LEDs, with different indium contents and different well widths, were grown, and the temperature-dependences of their electroluminescence (EL) spectra at different fixed injection currents are investigated to explore the effect of the indium content and well width on the carrier transferring and recombining mechanism in such LEDs
To produce high-performance InGaN-based LEDs that emit photons at a fixed wavelength, two blue InGaN/GaN MQW-based LED samples, with different indium contents and well widths, have been grown, and the temperature-dependences of their EL spectra investigated at different injection currents
Summary
InGaN/GaN multiple quantum wells (MQWs) acting as active layers in light emitting diodes (LEDs) and laser diodes (LDs) have attracted significant attention, since by tuning the indium composition in an InGaN well layer, the whole spectral range, corresponding to near-infrared to visible and up to near-ultraviolet emissions, can be covered by the nitride system[1,2,3,4]. InGaN/GaN MQW-based blue LEDs have been extensively employed in full-color displays, back-lighting, general illumination, and in other applications of optoelectronic devices, at the same time, green, yellow, and even red long-wavelength InGaN/GaN MQW-based LEDs that are used when preparing white LEDs, are attracting much research interest; due to the large discrepancy in atomic size between indium and gallium, and a large lattice mismatch of 11% between InN and GaN, either a phase separation or a slight composition fluctuation always occurs in the InGaN well layers, and this results in generation of the structural defects acting as non-radiative recombination centers. To produce a high-efficiency blue LED, two InGaN/GaN MQW-based LEDs, with different indium contents and different well widths, were grown, and the temperature-dependences of their electroluminescence (EL) spectra at different fixed injection currents are investigated to explore the effect of the indium content and well width on the carrier transferring and recombining mechanism in such LEDs
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