| المؤلفون: |
Singh VK; Department of Physics, Institute of Science, Banaras Hindu University, Varanasi 221005, India., Pendurthi R; Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802, United States., Nasr JR; Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802, United States., Mamgain H; WITec GmbH, Lise-Meitner-Str. 6, D-89081 Ulm, Germany., Tiwari RS; Department of Physics, Institute of Science, Banaras Hindu University, Varanasi 221005, India., Das S; Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802, United States.; Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States.; Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, United States., Srivastava A; Department of Physics, Institute of Science, Banaras Hindu University, Varanasi 221005, India. |
| مستخلص: |
Transition-metal dichalcogenides (TMDCs) with atomic thickness are promising materials for next-generation electronic and optoelectronic devices. Herein, we report uniform growth of triangular-shaped (∼40 μm) monolayer WS 2 using the atmospheric-pressure chemical vapor deposition (APCVD) technique in a hydrogen-free environment. We have studied the optical and electrical behaviors of as-grown WS 2 samples. The absorption spectrum of monolayer WS 2 shows two intense excitonic absorption peaks, namely, A (∼630 nm) and B (∼530 nm), due to the direct gap transitions at the K point. Photoluminescence (PL) and fluorescence studies reveal that under the exposure of green light, monolayer WS 2 gives very strong red emission at ∼663 nm. This corresponds to the direct band gap and strong excitonic effect in monolayer WS 2 . Furthermore, the efficacy of the synthesized WS 2 crystals for electronic devices is also checked by fabricating field-effect transistors (FETs). FET devices exhibit an electron mobility of μ ∼ 6 cm 2 V -1 s -1 , current ON/OFF ratio of ∼10 6 , and subthreshold swing (SS) of ∼641 mV decade -1 , which are comparable to those of the exfoliated monolayer WS 2 FETs. These findings suggest that our APCVD-grown WS 2 has the potential to be used for next-generation nanoelectronic and optoelectronic applications. |
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