Light-activated two-level resistance switching: An extremely sensitive GaAs/AlGaAs solid-state photon counter

Abstract
Data are presented on a new type of extremely quiet and sensitive GaAs/AlGaAs photodetector. The photoresponse of the device is controlled by a hole trap in a tunnel barrier. Capture of a single photoinjected hole by the trap gates the device and produces an easily measured current pulse which can be counted by a conventional pulse-counting apparatus. There is only one detectable trap in a photoactive area of ≂400 μm2. However, due to electric field channeling effects the trap collects photoinjected holes with a 1% efficiency in the active region. The absence of measurable dark counts in a 25 h period at 77 K establishes a minimum detectable photon flux <0.001 photons/s at 8200 Å.