Gate‐Modulated Polarity Transition and Polarization‐Sensitive Photodetection Enabled by Sandwiching Anisotropic GeSe in vdW Heterojunction

The ability to modulate the polarity of carrier transport and photo‐response in assembled heterostructure devices remains a huge challenge for the development of multifunctional optoelectronics. Herein, a polarity‐switchable and polarization‐sensitive photodetector is developed based on a van der Waals (vdW) MoTe2/GeSe/MoS2 sandwich heterostructure. By varying the gate voltage, an anti‐bipolar transfer characteristic is obtained with significant peak‐valley current ratio (PVCR) exceeding 104, showing the extraordinary potential to realize electronic functions in logic circuits. Under 635 nm laser irradiation, the device exhibits a gate‐controlled polarity transition of photocurrent, namely, the sign reversal of photocurrent occurs by changing the gate voltage. Furthermore, the device achieves broadband photovoltaic effect and high photodetection performance with responsivity (R) of 723 mA·W−1, noise spectral density (Sn) of 1 fA Hz−1/2, and specific detectivity (D*) of 2.3×1012 Jones in the absence of external bias, which greatly outperforms the MoTe2/MoS2 device. Leveraging the in‐plane anisotropic structure of GeSe, the device is also endowed with an additional capability of polarization‐sensing for linearly polarized laser, possessing a high polarization ratio (PR) value of 11.2. Thus, this work proposes an effective and facile strategy to realize the gate‐modulated polarity transition and polarization‐sensitive photodetection, offering a broad perspective for multifunctional integrated applications. Anti‐ambipolar behavior and polarization‐sensitive properties are achieved by sandwiching p‐GeSe in a MoTe2/MoS2 heterojunction, with a peak‐to‐valley current ratio of more than104, polarization ratio as high as 11.2, and noise spectral density as low as 1 fA Hz‐1/2. Photocurrent polarity reversal through external voltage modulation provides the basis for multifunctional integration applications.