A GaAs/AlAs/AlGaAs and GaAs/AlGaAs stacked quantum well infrared photodetector for 3–5 and 8–14 μm detection

Abstract

A new two-color n-type GaAs/AlAs/AlGaAs double barrier quantum well (DBQW) and bound-to-miniband GaAs/AlGaAs quantum well infrared photodetector (QWIP) with photovoltaic (PV) and photoconductive (PC) dual-mode operation in the 3–5 and 8–14 μm atmospheric spectral windows has been demonstrated in this work. It consists of a stack of the midwavelength infrared (MWIR) QWIP and the long-wavelength infrared (LWIR) QWIP. The PV detection scheme uses transition from the ground bound state to the first quasi-bound excited state for the MWIR-QWIP. The PC detection scheme has two different transitions, one identical to the PV mode detection scheme while the other uses transition from the ground bound state to the miniband state of the superlattice barrier LWIR-QWIP. The peak responsivity for the PV mode was found to be 17 mA/W at λp=4.1 μm and T=50 K with a bandwidth Δλ/λp=15%. The peak responsivities for the PC mode were found to be 25 mA/W at λp=4.1 μm, Vb=1.0 V, and 0.12 A/W at λp=11.6 μm, Vb=3.2 V, and at T=50 K, with a bandwidth Δλ/λp=18%. The PV responsivity was found to be 68% of the PC responsivity at λp=4.1 μm and T=50 K, demonstrating the ability for efficient PV mode operation at 3–5 μm by using the DBQW structure. This is the highest ratio reported for the spectral region of 3–5 μm wavelength with a DBQW structure.