Effects of oxygen contamination on monolayer GeSe: A computational study

Pan

et al. 2022

J. Electron. Mater.

Binary IV-VI chalcogenides MXs (SnS, SnSe, SnTe, GeS, GeSe, and GeTe), as a family two-dimensional (2D) semiconductor material, have a proper bandgap, high carrier mobility, stability in ambient conditions, and a pucker structure, hence they are potential channel materials for the next-generation electronic and optoelectronic devices. 2D MXs devices should directly contact the metal electrodes to inject suitable types of carriers, on account of the random dopant fluctuation. However, a Schottky contact is always formed at the interface, which degrades the performance of the MXs devices. Herein, we report the contact characteristics of the MXs field-effect transistors (FETs) with Graphene(Gr)/Ag/Au electrodes (twointerface model) by using quantum transport calculations and density functional theory. At the vertical interface, the MXs FETs form Van der Waals (vdW) contact type after being contacted with the Gr electrode, and an Ohmic contact is formed after being contacted with Ag and Au electrodes. At the lateral interface, the SnTe (armchair and zigzag), GeS (zigzag), and GeSe (zigzag) FETs with Gr electrode get a desired p-type Ohmic contact or quasi p-type Ohmic contact, suggestive of high device performance in such an MXs device. Our simulation provides a theoretical foundation for the choice of suitable electrodes in future ML MXs devices.

Section: Introductionmentioning

confidence: 74%

The Interfacial Properties of Monolayer MX–Metal Contacts

Guo

Pan

et al. 2022

J. Electron. Mater.

“…Previous calculations have indicated that oxidation could lead to severe local deformation on monolayer GeSe, and thus affecting the optoelectronic properties. 46 Herein, time-dependent Raman spectrum measurements were performed to examine the possible oxidation of GeSe nanosheets in air. For Raman characterizations, GeSe nanosheets were first loaded on the membrane filter and then exposed in air for various times.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Usually, the degradation of mechanical and electronic properties of the most 2D materials is caused by the oxidation under ambient conditions. Previous calculations have indicated that oxidation could lead to severe local deformation on monolayer GeSe, and thus affecting the optoelectronic properties . Herein, time-dependent Raman spectrum measurements were performed to examine the possible oxidation of GeSe nanosheets in air.…”

Section: Resultsmentioning

confidence: 99%

Ultrathin GeSe Nanosheets: From Systematic Synthesis to Studies of Carrier Dynamics and Applications for a High-Performance UV–Vis Photodetector

ACS Appl. Mater. Interfaces

Wang

et al. 2019

117

Owing to the attractive energy band properties, a black phosphorus (BP)-analogue semiconductor, germanium selenide (GeSe), shows a promising potential applied for optoelectronic devices. Herein, ultrathin GeSe nanosheets were systematically prepared via a facile liquid-phase exfoliation approach, with controllable nanoscale thickness. Different from BP, ultrathin GeSe nanosheets exhibit good stability under both liquid and ambient conditions. Besides, its ultrafast carrier dynamics was probed by transient absorption spectroscopy. We showed that the GeSe nanosheet-based photodetector exhibits excellent photoresponse behaviors ranging from ultraviolet (UV) to the visible regime, with high responsivity and low dark current. Furthermore, the detective ability of such a device can be effectively modulated by varying the applied bias potential, light intensity, and concentration of the electrolyte. Generally, our present contribution could not only supply fundamental knowledge of a GeSe nanosheet-based photoelectrochemical (PEC)-type device, but also offer guidance to extend other possible semiconductor materials in the application of the PEC-type photodetector.

“…Analogues to black phosphorus, the large bonding anisotropy of their layered crystals can be considered as a distorted NaCl structure, which lead to a strong anisotropy in electronic band structures . However, unlike phosphorene, GeSe surface is much more stable and resistant to oxidation . Earth abundant and environmental friendship make GeSe particularly attractive in applications of semiconductors .…”

Section: Introductionmentioning

confidence: 99%

Band Structure and Photoelectric Characterization of GeSe Monolayers

Mao

et al. 2017

Adv Funct Materials

145

129

Germanium selenide monolayer is promising in photoelectric applications for its natural p-type semiconductor and complicated band structures. Basic experimental investigations of few-to-monolayer germanium selenide are still absent; major scientific challenge is to develop of techniques for controllably thinned monolayers. In this study laser thinned monolayer germanium selenide on SiO 2 /Si substrates is demonstrated. A broad photoluminescence spectrum with eight continues peaks is observed from visible to infrared wavebands centered at ≈589, 655, 737, 830, 1034, 1178, 1314, and 1456 nm, respectively. First-principle calculations based on density functional theory illuminate the band structures of few-to-monolayer germanium selenide. Photoluminescence investigation combined with first-principle calculations indicates that the indirect to direct bandgap transition happens at few layers of N = 3. Current-voltage and photoresponse characteristics of monolayer based devices show 3.3 times the photosensitivity and much faster falling edges compared with those of the pristine nanosheet based devices. The present results provide useful insight into deep understanding of thickness dependent performances of germanium selenide monocrystalline.