Wenkai Zhu; Faguang Yan; Xia Wei; Quanshan Lv; Huai Yang; Kaiyou Wang
Abstract
Two-dimensional (2D) atomic crystals, such as graphene, black phosphorus and transition metal dichalcogenides (TMDCs) are attractive for use in optoelectronic devices, due to their unique optical absorption properties and van der Waals (vdWs) force between layers. Heterostructures based on layered semiconductors ...
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Two-dimensional (2D) atomic crystals, such as graphene, black phosphorus and transition metal dichalcogenides (TMDCs) are attractive for use in optoelectronic devices, due to their unique optical absorption properties and van der Waals (vdWs) force between layers. Heterostructures based on layered semiconductors provide a new platform for broadband high-performance photodetectors. In this work, graphene-MoTe2-WS2-graphene vdWs heterojunctions are fabricated for photodetection. The fundamental electric properties and the band structures of the heterojunctions are investigated and discussed. The devices show a high responsivity (≈ 140 mA W -1 at 825 nm), stable and broadband photodetection from UV to NIR wavelength range (300 - 1350 nm), fast response time of 186 µs and self-driven photodetectors. The scanning photocurrent microscopy maps are also employed to study the mechanism of photocurrent generation in the heterojunction. Our results reveal that the vdWs heterojunctions with graphene electrodes offer a new route to broadband detection, optical communication and energy harvesting applications.

Karen M. Gambaryan
Abstract
For the thermophotovoltaic (TPV) and other mid-infrared applications, the narrow bandgap quantum dot (QD) diode structures and photoresistors (PR) based on InAsSbP alloys and InAs industrial substrates are fabricated and investigated. For the nucleation of InAsSbP composition strain-induced QDs in Stranski–Krastanow ...
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For the thermophotovoltaic (TPV) and other mid-infrared applications, the narrow bandgap quantum dot (QD) diode structures and photoresistors (PR) based on InAsSbP alloys and InAs industrial substrates are fabricated and investigated. For the nucleation of InAsSbP composition strain-induced QDs in Stranski–Krastanow growth mode, as well as at the growth of emitter epilayer lattice-matched with the InAs(100) substrate, the modified liquid phase epitaxy (MLPE) technique is employed. The HR-SEM and AFM microscopes are used for characterization. The grown QDs surface density equals to (3-8)×109 cm -2 , with height and width dimensions ranges from 4 nm to 15 nm and 10 nm to 35 nm, respectively. The current-voltage characteristics and photoresponse spectra of QD TPV and PR structures are also explored. The redshift of the absorption edge, as well as enlargement toward the short wavelength region is revealed for both QD-based devices. The quantitative calculations show increasing of QD-based TPV structures efficiency up to 16% compared with the same structures without QDs.
