Linear array of charge sensitive infrared phototransistors for long wavelength infrared detection

Abstract

Infrared has been deeply involved in frontier research, modern technologies, and human society, which requires sensitive infrared detection and sensing, in particular, array imaging. A charge-sensitive infrared phototransistor (CSIP) device is made of a GaAs/AlGaAs double quantum well and has been shown to exhibit much larger infrared photoresponsivity than conventional infrared photodetectors, attributable to its built-in amplification mechanism of large transconductance. In this work, we propose and demonstrate a linear array architecture of long wavelength CSIPs with each pixel directly addressable via its reset gate. The performance of a prototype 1×8 linear array of CSIPs is studied at 5 K, and each pixel shows a large photoresponsivity of >50 A/W at the peak wavelength of λ=11 μm, nearly two orders higher than conventional detectors. Using a home-made multi-channel pulse generator, the array is operated at a typical frame rate of ∼5 ms, without the necessity of using cryogenic readout circuits. Besides, the fabrication of the proposed CSIP array requires only state-of-the-art planar technology; our work, therefore, provides a promising solution to realize very sensitive and small-scale array infrared imaging for sensitive long-wavelength infrared applications.