Capacitive infrared photodetector for room temperature operation

摘要

We report a self-assembled semiconductor nanowire photodetector that detects infrared light at room temperature by registering a change in capacitance upon illumination. Its light-to-dark capacitance ratio exceeds 2.5 at a signal frequency of 75 kHz and gradually decays to 1 beyond 200 kHz. This detector also exhibits "frequency-selectivity" since it is more responsive to photons with energies close to the nanowire's effective bandgap than to higher energy photons. Such a light-sensitive capacitor, unlike a light-sensitive resistor, can be used in a resonant parallel inductor-capacitor circuit to yield giant light-to-dark contrast ratio even when the light-to-dark capacitance ratio is relatively small.