A Photoconductor‐Type Position Recognition Mechanism with the Intrinsic High Gain for the Development of Ultra‐Sensitive Light Position Detection.

Position‐sensitive detectors (PSDs) are widely used in optical inspection applications, such as precise measurement of distance and angle, surface profiling, and motion tracking, etc. The lateral photovoltaic effect is the mechanism employed by most PSDs to determine position, but its gain‐free nature hinders weak‐light detection and applications. Here, a new position recognition mechanism with an intrinsic high gain is proposed and employ it to design a weak‐light and large‐size photoconductor‐type PSD. The position recognition is established by the intrinsic link between the gain and channel length in a photoconductor, and the designed linear correlation between the channel length and position. The photoconductor‐type graphene/Si PSD based on the recognition mechanism shows an active length of over 1 mm, a high spatial position resolution at the sub‐micrometer level, and a low detection limit power of 100 pW. Compared with Si PSDs, the gain of the photoconductor‐type PSD is improved by 3–4 orders of magnitude. In addition, the operational wavelength range of the PSD is expanded to include the near‐infrared region, specifically at 1300 and 1550 nm. The new position recognition mechanism paves the way for the development of ultra‐sensitive light position detection. [ABSTRACT FROM AUTHOR]