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▲ [7a-A404-8] GeSe/MoS2 heterojunction diode for optoelectronic applications
Keywords:GeSe/MoS2 heterostructure, Photodetector
Heterostructure engineering of two-dimensional (2D) layered materials offers an exciting opportunity to take advantage of each building block for fabricating new electronic and optical devices. The p-n junction diode constructed by heterostructures of 2D layered materials (e.g., MoS2/WSe2, MoS2/black phosphorus,) have been demonstrated to be excellent candidates for high-sensitive photodetectors with broad spectral response [1,2]. Recently, IV family monochalcogenides (e.g., GeS and GeSe) have been introduced as a new member of 2D material family and attracted much attention for the highly sensitive photodetector applications. The p-type semiconductor 2D GeSe has an orthorhombic structure with the band gap at around 1.1 eV. Accompanied by its strong light absorption property, the GeSe shows high-potential working as a photodetector with a broadband response from ultra-violate to near-infrared spectral regions [3]. By stacking n-type MoS2 and p-type GeSe, the formation of heterojunction diode is highly promising with unique optoelectronic properties.
2. Results and Discussion
Here, the highly sensitive-photodetector based on GeSe/MoS2 heterojunction has been demonstrated. We fabricated the multilayer GeSe flakes on PDMS film and few layer MoS2 on silicon substrate by using the mechanical exfoliation method and then transfered GeSe onto MoS2. The GeSe/MoS2 heterojunction based field-effect transistors (GeSe/MoS2 heterojunction-FETs) were prepared using the electron-beam lithography (Inset of Fig. 1(a)). Fig. 1a is the typical transfer characteristic behavior of GeSe/MoS2 device, and anti-ambipolar behavior can be seen. The typical on/off ratio (Ion/off) of this heterostructure FET is larger than 104 (Fig. 1(a)). The GeSe/MoS2 heterostructured FETs show obvious rectification behavior with rectification ratio larger than 5000, which was different from GeSe and MoS2 FETs, indicating that the hetero-diode was formed. Obvious photovoltaic effect was also observed. Furthermore, the GeSe/MoS2 hetero-diode also exhibits strong (Fig. 1(b)) and broadband photoresponse with the photoresponsivity reaching 3 × 104 A/W at 500 nm. These excellent properties of high photoresponsivity and high rectification ratio indicate that the GeSe/MoS2 heterojuction diode is a highly qualified candidate for the optoelectronic applications.
2. Results and Discussion
Here, the highly sensitive-photodetector based on GeSe/MoS2 heterojunction has been demonstrated. We fabricated the multilayer GeSe flakes on PDMS film and few layer MoS2 on silicon substrate by using the mechanical exfoliation method and then transfered GeSe onto MoS2. The GeSe/MoS2 heterojunction based field-effect transistors (GeSe/MoS2 heterojunction-FETs) were prepared using the electron-beam lithography (Inset of Fig. 1(a)). Fig. 1a is the typical transfer characteristic behavior of GeSe/MoS2 device, and anti-ambipolar behavior can be seen. The typical on/off ratio (Ion/off) of this heterostructure FET is larger than 104 (Fig. 1(a)). The GeSe/MoS2 heterostructured FETs show obvious rectification behavior with rectification ratio larger than 5000, which was different from GeSe and MoS2 FETs, indicating that the hetero-diode was formed. Obvious photovoltaic effect was also observed. Furthermore, the GeSe/MoS2 hetero-diode also exhibits strong (Fig. 1(b)) and broadband photoresponse with the photoresponsivity reaching 3 × 104 A/W at 500 nm. These excellent properties of high photoresponsivity and high rectification ratio indicate that the GeSe/MoS2 heterojuction diode is a highly qualified candidate for the optoelectronic applications.