Field control in piezoelectric [111]-oriented InGaAs/GaAs MQW and superlattice devices

In [111]-oriented InGaAs/GaAs multiple quantum wells and superlattices, the field in the wells, barriers, and the average electric field, are deduced using simple analytical expressions. The influence of the design parameters on the conduction-band profile and optoelectronics properties of strained piezoelectric p-i-n diodes is presented. In samples with negative average electric field, transient photocurrent response and photocapacitance-voltage characteristics clearly reveal that carriers accumulate at the extremes of the active region, giving rise to a long-range screening effect of the field in the wells. Coupled quantum wells and piezoelectric superlattices have been studied by photocapacitance techniques, and the revealed features were explained as due to carrier sequential tunneling and accumulation processes.