Quantum-dot infrared photodetectors with p-type-doped GaAs barrier Layers

We investigate the effects of p-type-doping concentration in the GaAs barrier layer on the multistack InAs-GaAs quantum-dot infrared photodetectors (QDIPs). The dark current decreases with the p-type-doping density in the GaAs barrier layer. The QDIP with five stacks and a p-type-doping concentration of 1×10/sup 16/ cm/sup -3/ in the GaAs barrier layer and show an observable spectral response with a peak responsivity of 0.5 A/W at 6 μm. With increasing the p-type-doping density up to 1×10/sup 17/ cm/sup -3/, the QDIP structure shows a reduced photocurrent and a nondetectable response. The QDIPs with p-type-doped GaAs barrier layers and different stack numbers exhibit a saturation photocurrent, where the saturation voltage is proportional to the stack number.