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To improve the internal quantum efficiency of green light-emitting diodes, we present the numerical design and analysis of bandgap-engineered W-shaped quantum well. The numerical results suggest significant improvement in the internal quantum efficiency of the proposed W-LED. The improvement is associated with significantly improved hole confinement due to the localization of indium in the active region, leading to improved radiative recombination rate. In addition, the proposed device shows reduced defect-assisted Shockley-Read-Hall (SRH) recombination rate as well as Auger recombination rate. Moreover, the efficiency rolloff in the proposed device is associated with increased built-in electromechanical field.

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We present the numerical effect of the polarity of the built-in field on the GaN-based light-emitting diodes (LEDs). The results show that, in comparison to the Ga-polar device, the p-down N-polar device shows significant improvement in electronic and optical characteristics. In N-LED, the turn-on voltage, internal quantum efficiency and radiative recombination rate is improved by 6%, three times at 100 A cm−2 and 194%, respectively. It is shown that the effective barrier heights and energy band offsets are the governing reason behind the significant improvement in N-polar devices.

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