The effect of the first barrier thickness on resonanceudtunnelling and carrier accumulation in undoped singleudquantum well infrared photodetectors

摘要

The electrical behaviour of an undoped, MBE-grown, asymmetric thickness-double barrier single quantum well (QW) infrared photodetector structures were studied. The structures consisted of 100-200 A thick Al0.27Ga0.73As emitter barrier, a 40 A thick GaAs quantum well (QW) and a 500 A thick Al0.27Ga0.73As collector barrier. In order to describe the current generation mechanisms, the resonance current and the non-resonance current from emitter contact to QW, and the field emission current from the QW were simulated by numerical calculations. Calculated and the measured currents were in good agreement. Our result showed that the QW carrier density increased with reduced emitter barrier thickness enhancing the detector performance but at the cost of increased noise levels with dark current.