Semiconductor nanowire field-effect transistors represent a promising platform for the development of room-temperature (RT) terahertz (THz) frequency light detectors due to the strong nonlinearity of their transfer characteristics and their remarkable combination of low noise-equivalent powers (<1 nW Hz^−1/2) and high responsivities (>100 V/W). Nano-engineering an NW photodetector combining high sensitivity with high speed (sub-ns) in the THz regime at RT is highly desirable for many frontier applications in quantum optics and nanophotonics, but this requires a clear understanding of the origin of the photo-response. Conventional electrical and optical measurements, however, cannot unambiguously determine the dominant detection mechanism due to inherent device asymmetry that allows different processes to be simultaneously activated. Here, we innovatively capture snapshots of the photo-response of individual InAs nanowires via high spatial resolution (35 nm) THz photocurrent nanoscopy. By coupling a THz quantum cascade laser to scattering-type scanning near-field optical microscopy (s-SNOM) and monitoring both electrical and optical readouts, we simultaneously measure transport and scattering properties. The spatially resolved electric response provides unambiguous signatures of photo-thermoelectric and bolometric currents whose interplay is discussed as a function of photon density and material doping, therefore providing a route to engineer photo-responses by design.

半导体纳米线场效应晶体管由于其传输特性的强非线性以及低噪声等效功率（<1 id =109>− ^1/2 ) 和高响应度 (>100 V/W)。纳米工程纳米线光电探测器在室温太赫兹范围内将高灵敏度与高速（亚纳秒）相结合，对于量子光学和纳米光子学的许多前沿应用来说是非常理想的，但这需要清楚地了解光响应的起源。然而，由于固有的设备不对称性允许同时激活不同的过程，传统的电学和光学测量无法明确确定主要的检测机制。在这里，我们通过高空间分辨率（35 nm）太赫兹光电流纳米显微镜创新地捕捉单个 InAs 纳米线的光响应快照。通过将太赫兹量子级联激光器与散射型扫描近场光学显微镜（s-SNOM）耦合并监测电学和光学读数，我们可以同时测量传输和散射特性。空间分辨的电响应提供了光热电和测辐射热电流的明确特征，其相互作用被讨论为光子密度和材料掺杂的函数，因此提供了通过设计来设计光响应的途径。