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RISS 인기검색어
- 검색키워드
- 저자 : Krishna Bahadur Rai (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
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Influence of Hydrophobicity on the Chemical Treatments of Graphene
Krishna Bahadur Rai,Ishwor Bahadur Khadka,김은혜,안성준,김현우,안종렬 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.1
The defect-free transfer of graphene grown by using chemical vapor deposition is essential for its applications to electronic devices. For the reduction of inevitable chemical residues, such as polar molecules and ionized impurities resulting from the transfer process, a hydrophobic polydimethylsiloxane (PDMS) film was coated on a SiO2/Si wafer. The hydrophobic PDMS film resulted in fewer defects in graphene in comparison to a bare SiO2/Si wafer, as measured with Raman spectroscopy. We also studied the influence of the hydrophobic PDMS film on the chemical doping of graphene. Here, nitric acid (HNO3) was used to make p-type graphene. When graphene was transferred onto a SiO2/Si wafer coated with the hydrophobic PDMS film, fewer defects, compared to those in graphene transferred onto a bare SiO2/Si wafer, were created in grapheme by HNO3 as measured with Raman spectroscopy. The experiments suggest that when graphene is transferred onto a hydrophobic film, the number of defects created by chemical molecules can be reduced.
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Insight of cleaning, doping and defective effects on the graphene surface by using methanol
Rai, Krishna Bahadur,Khadka, Ishwor Bahadur,Koirala, Agni Raj,Ray, Schindra Kumar Techno-Press 2021 Advances in materials research Vol.10 No.4
Graphene has attracted enormous interest to researchers because of its remarkable electrical, mechanical, and optical properties. Chemical vapor deposition (CVD) method was used to synthesize the graphene. The methanol (CH<sub>3</sub>OH) was used to investigate the cleaning, doping and defective effect in the graphene surface. The samples were characterized by X-ray diffraction patterns (XRD), field emission scanning electron microscope (FESEM) images, Xray photoelectron spectroscopy (XPS) measurements, and Raman spectroscopy. XRD indicates the introduction of oxygen in graphene layer. FESEM images of samples suggest the sheet like morphology. XPS measurements confirm the existence of large number of oxygen containing functional groups (C=O, COOH, and C-O) and C-C in the graphene surface. The Raman spectra confirm the n-doping and cleaning effects on graphene surface through the red shifts of G and 2D peaks. Furthermore, the optical images were used to observe the residues in graphene. The residues are obtained due to adsorption of CH<sub>3</sub>OH in graphene surface. Therefore, this work provides a simple and effective approach to investigate the cleaning, doping and defective effects on the surface of graphene using CH<sub>3</sub>OH solvent that can be applied in tunable electronic devices and gas sensor.
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Electronic Structure of Graphene Grown on a Hydrogen-terminated Ge (110) Wafer
Sung Joon Ahn,Hyun Woo Kim,Ishwor Bahadur Khadka,Krishna Bahadur Rai,Joung Real Ahn,Jae-Hyun Lee,Seog Gyun Kang,Dongmok Whang 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.5
Using angle-resolved photoemission spectroscopy, we studied the electronic structure of graphene grown on a Ge (110) wafer, where a single-crystal single-layer graphene was recently grown using chemical vapor deposition. The growth mechanism of the single-layer single-crystal graphene was related to the hydrogen termination of the Ge (110) surface. To further understand the growth mechanism, we measured the electronic structure of the graphene-covered Ge (110) wafer in a vacuum as a function of the increasing temperature, which led to a deintercalation of the hydrogen atoms. Furthermore, we measured the electronic structure after the reintercalation of the hydrogen atoms between the Ge substrate and graphene. These findings show that hydrogen is intercalated between the Ge substrate and graphene after the growth of graphene using chemical vapor deposition.
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