CONDUCTION-BAND ENGINEERING IN PIEZOELECTRIC[111] MULTIPLE-QUANTUM-WELL P-I-N PHOTODIODES

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 electri c field (AEF) in the p-i-n active region (MQWs within the intrinsic re gion) is obtained. The existence of two different potential envelopes, corresponding to a positive or to a negative sign of the AEF, and giv ing rise to clearly different optical and electronic properties, is de monstrated. In samples with negative AEF, as compared to structures wi th positive AEF, larger reverse voltages are needed to quench the phot oluminescence and to enhance the p-i-n photocurrent. An analysis of bo th transition energies and intensities, versus bias, clearly indicates that in samples with a negative AEF carriers accumulate at the extrem es of the active region, giving rise to a long-range screening effect of the field in the wells. (C) 1994 American Institute of Physics.