Conduction-band engineering in piezoelectric [111] multiple quantum well p-i-n photodiodes

Abstract

The influence of the design parameters on the conduction-band profile and optoelectronic properties of [111]-oriented InGaAs/GaAs p-i(MQW)-n diodes is presented. An analytical expression for the average electric field (AEF) in the p-i-n active region (MQWs within the intrinsic region) is obtained. The existence of two different potential envelopes, corresponding to a positive or to a negative sign of the AEF, and giving rise to clearly different optical and electronic properties, is demonstrated. In samples with negative AEF, as compared to structures with positive AEF, larger reverse voltages are needed to quench the photoluminescence and to enhance the p-i-n photocurrent. An analysis of both transition energies and intensities, versus bias, clearly indicates that in samples with a negative AEF carriers accumulate at the extremes of the active region, giving rise to a long-range screening effect of the field in the wells.