Polarization-SensitiveSelf-Powered Type-II GeSe/MoS2 van der Waals HeterojunctionPhotodetector
2020
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 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 two-dimensional self-powered polarization-sensitive photodetector
is fabricated based on a stacked GeSe/MoS2 van der Waals
(vdW) heterojunction which facilitates efficient separation and transportation
of the photogenerated carriers because of 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 an external quantum
efficiency of 24.2%. Furthermore, a broad spectral photoresponse is
extended from 380 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 of 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.
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