Single InAs nanowire room-temperature near-infrared photodetectors

Here we report InAs nanowire (NW) near-infrared photodetectors having a detection wavelength up to ∼1.5 μm. The single InAs NW photodetectors displayed minimum hysteresis with a high I_on/I_off ratio of 10⁵. At room temperature, the Schottky-Ohmic contacted photodetectors had an external photoresponsivity of ∼5.3 × 10 ³ AW^-1, which is ∼300% larger than that of Ohmic-Ohmic contacted detectors (∼1.9 × 10³ AW^-1). A large enhancement in photoresponsivity (∼300%) had also been achieved in metal Au-cluster-decorated InAs NW photodetectors due to the formation of Schottky junctions at the InAs/Au cluster contacts. The photocurrent decreased when the photodetectors were exposed to ambient atmosphere because of the high surface electron concentration and rich surface defect states in InAs NWs. A theoretical model based on charge transfer and energy band change is proposed to explain this observed performance. To suppress the negative effects of surface defect states and atmospheric molecules, new InAs NW photodetectors with a half-wrapped top-gate had been fabricated by using 10 nm HfO₂ as the top-gate dielectric.