Photovoltaic and photoconductive dual-mode operation GaAs quantum well infrared photodetector for two-band detection

Abstract
A new photoconductive (PC) and photovoltaic (PV) dual-mode operation quantum well infrared photodetection (DM-QWIP) using an enlarged GaAs (110 Å) quantum well and enlarged Al0.25Ga0.75As (875 Å) barrier layer has been developed for two-color intersubband detection. The detection scheme uses transitions from the ground-state and the first excited-state inside the enlarged GaAs quantum well to the continuum states slightly above the AlGaAs barrier layers. The detectivity Dλ* for the PV mode was found to be 1.5×109√Hz/ W at the peak response wavelength λp=7.7 μm and T=77 K, while the values of Dλ* for the PC mode were found to be 2×1010, 1×1010 cm√Hz/W for Vb=1,2 V at λp=12 μm and T=77 K, respectively.