Ultra‐Thin GeSe/WS₂ Vertical Heterojunction with Excellent Optoelectronic Performances

Abstract

Heterostructural engineering of atomically thin 2D materials offers an exciting opportunity to fabricate atomically sharp interfaces for optoelectronic devices. Herein, GeSe/WS2 heterojunction devices composed of 2D WS2 (n‐type) and few‐layer GeSe (p‐type), are fabricated by transferring mechanically exfoliated GeSe to chemical vapor deposition (CVD)‐grown WS2. Excellent rectification behavior is observed from the I−V characteristics of the GeSe/WS2 heterojunction devices. The reverse photocurrent increases more rapidly than the forward photocurrent under a 635 nm laser illumination, indicating an effective separation of the photogenerated carriers under a minus bias. A large photocurrent on‐off ratio of 103 at −5 V bias, a high responsivity (Rλ) of 1.1 A W−1, a considerable specific detectivity (D*) of 1.3×1010 Jones, and a high external quantum efficiency (EQE) of 214.8%, are obtained. Owing to the large built‐in potential of the heterojunction, efficient charge transfer is achieved from the abrupt interfaces even though vastly different materials are used in the van der Waals (vdW) heterostructure. A convenient route is demonstrated for the preparation of ultra‐thin GeSe/WS2 vdW heterojunctions. The results reveal great potential of the present GeSe/WS2 vertical heterojunction for future applications in optoelectronics.

Abnormal behavior of preferred formation of the cationic vacancies from the interior in a γ-GeSe monolayer with the stereo-chemical antibonding lone-pair state

“…Group IV monochalcogenides MX (M = Ge, Sn, Pb; X = S, Se, Te) are a family of emerging 2D layered materials which are gaining extensive interest in thermoelectric, 1,2 photocatalysis, 3,4 and ferroelectric 5,6 fields. Among the various MXs, GeSe deserves particular attention, owing to recent papers reporting on its outstanding photovoltaic efficiency, 7 excellent optoelectronic properties, 8 and electric-field induced room temperature antiferroelectric–ferroelectric phase transition, 9 as well as its inherent chemical stability and environmental sustainability.…”

Integration of Self‐Passivated Topological Electrodes for Advanced 2D Optoelectronic Devices

“…Notably, our BWB device is compatible with various optimization schemes, such as dielectric engineering [41] and heterostructure [43] WSe 2 /𝛼-In 2 Se 3 , [44] MoSe 2 /WSe 2 /4H-SiC, [45] WS 2 , [46] Gr/WS 2 /Gr, [22] WS 2 /Si, [47] WS 2 /PbS QDs, [48] ReSe/WSe 2 , [49] WSe 2 , [50] WSe 2 /MoS 2 , [51] SnSe/Bi 2 Te 3 , [6] and GeSe/WS 2 . [52] h) Photoswitching curves of the BWB device for 200 cycles.…”

Preparation of Mixed Few-Layer GeSe Nanosheets with High Efficiency by the Thermal Sublimation Method

“…The A g 3 and A g 1 peaks are assigned to the transverse optical mode in the A g symmetry, and the B 3g 1 peak is assigned to the transverse optical mode in the B 3g symmetry, which are basically consistent with the previous reports. 26,27 Generally, the intensity and full width at half maximum (fwhm) of Raman peaks of GeSe films are proportional to their thicknesses. This is because Raman scattering becomes weak as the thickness of the GeSe film becomes thinner, and the sublimation-induced defects are also responsible for this result.…”