Polarization-Sensitive Self-Powered Type-II GeSe/MoS2 Van der Waals Heterojunction Photodetector

摘要： Polarization-sensitive photodetectors are highly desirable for high performance optical signal capture and stray light shielding in order to enhance the capability for detection and identification of targets in the dark, haze and other complex environments. Usually, filters and polarizers are utilized for conventional devices to achieve polarization-sensitive detection. Herein, to simplify the optical system, a 2-D self-powered polarization-sensitive photodetector is fabricated based on a stacked GeSe/MoS2 van der Waals (vdWs) heterojunction which facilitates efficient separation and transportation of the photogenerated carriers, due to type-II band alignment. Accordingly, a high performance self-powered photodetector is achieved with merits of a very large on-off ratio photocurrent at zero bias of currently 104 and a high responsivity (Rλ) of 105 mA/W with the external quantum efficiency (EQE) of 24.2%. Furthermore, a broad spectral photoresponse is extended from 380 nm to 1064 nm owing to the high absorption coefficient in a wide spectral region. One of the key benefits from these highly anisotropic orthorhombic structures of layered GeSe is self-powered polarization sensitive detection with a peak/valley ratio up to 2.95. This is realized irradiating with a 532 nm wavelength laser with which a maximum photoresponsivity of up to 590 mA/W is reached when the input polarization is parallel to the armchair direction. This work provides a facile route to fabricate self-powered polarization-sensitive photodetectors from GeSe/MoS2 vdW heterojunctions for integrated optoelectronic devices.