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

Abstract

In this letter, 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 × 1016 cm-3 in the GaAs barrier layer and show an observable spectral response with a peak responsivity of 0.5 A/W at 6μm. With increasing the p-type-doping density up to 1 × 1017 cm-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. © 2005 IEEE.