Multifunctional GeAs/WS₂ Heterojunctions for Highly Polarization-Sensitive Photodetectors in the Short-Wave Infrared Range

Abstract

Polarization-sensitive photodetectors in the infrared range have attracted considerable attention because of their unique and wide application prospects in polarization sensors and remote sensing. However, it is challenging to achieve short-wave infrared polarization detection as most polarization-sensitive photodetectors are based on transition-metal dichalcogenide (TMD) materials with in-plane symmetric crystal structure and sizable band gap (1–2 eV). In this work, we design a type-II GeAs/WS2 heterojunction realizing superior self-driven polarization-sensitive photodetection in the short-wave infrared region. The device shows obvious rectifying behavior with a rectification ratio of 1.5 × 104 in the dark and excellent photoresponse characteristics in a broad spectral range. Accordingly, the high responsivity of 509 mA/W, large on/off ratio of 103, a high EQE of 99.8%, and a high specific detectivity of 1.08 × 1012 Jones are obtained under 635 nm laser irradiation. Taking advantage of the narrow band gap of GeAs with an anisotropic structure, the detection spectral coverage can be extended from the visible to the short-wave infrared range (635–1550 nm). Further, the GeAs/WS2 heterojunction shows high polarization sensitivity with an anisotropic photocurrent ratio of 4.5 and 3.1 at zero bias under 1310 and 1550 nm laser irradiation, respectively, which is much higher than that of reported polarization-sensitive photodetectors in the infrared region. This work provides an effective route using low-symmetry 2D materials with narrow band gap and anisotropic structure to design van der Waals (vdW) heterojunctions, realizing multifunctional optoelectronics for rectifying, photovoltaics, and polarization-sensitive photodetectors with spectral coverage up to 1550 nm.

Van der Waals Heterostructures With Built‐In Mie Resonances For Polarization‐Sensitive Photodetection

“…[9] Fortunately, some TMDs such as ReS 2 with intrinsic inplane anisotropy [10][11][12] enrich the devices for polarization-sensitive detection. [13][14][15][16] Utilizing intrinsic anisotropy to realize polarization detection is insensitive; so, this limitation triggers the combination of TMDs with metallic plasmonic structures [17][18][19] or dielectric Mie-type structures [20][21][22][23] to enhance light-matter interactions. [24,25] By tuning the resonant modes through structural design, optical nanostructures facilitate wavelength-dependent or polarization-sensitive photodetection of TMDs.…”

Engineering the Polarization Sensitivity in All‐2D Photodetectors Composed of Semimetal MoTe2 and Semiconductor WS2

“…[13,24] For example, MoS 2 -based photodetector with anisotropic gold nanoellipses offers the capability of polarized light detection with a photocurrent anisotropic ratio of 1.45. [25] Recently, the construction of van der Waals heterostructures (vdWHs) [26][27][28][29][30][31] composed of anisotropic 2D materials, such as GeSe/MoS 2 [32] and GeAs/lnSe, [33] has also been demonstrated to improve the polarization sensitivity by 3-10 times compared to photodetectors based on single anisotropic material. Moreover, the gate voltage can act as an effective knob to modulate the anisotropic photocurrent and dichroism ratio in anisotropic 2D materials.…”

Reconfigurable and Broadband Polarimetric Photodetector

“…[ 11 ] However, the performance in terms of the polarization sensitivity, response speed, and spectral coverage is still much limited in these detectors based on individual low symmetry 2D materials such as bP, GeSe, GeAs, etc. [ 12–14 ] Further, the construction of heterojunctions composed of anisotropic 2D materials such as GeAs/InSe, [ 15 ] GeAs/WS 2 , [ 16 ] WSe 2 /ReSe 2 , [ 17 ] WSe 2 /TaIrTe 4 /MoS 2 , [ 18 ] and graphene/PdSe 2 /Ge [ 19 ] has been demonstrated to exhibit self‐powered and polarization‐sensitive photodetection performance benefiting from their photovoltaic effect and anisotropic components, but it is still challenging to simultaneously achieve the high sensitivity, fast speed, and broad spectral coverage in single device. Moreover, it can be of great importance to adjust the operation mode, mechanism, or photo‐gain through the external bias in one chip to adapt to the complex application scenes.…”