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Role of cooling rate in selective synthesis of graphene and carbon nanotube on Fe foil using hot filament chemical vapor deposition
, Article 2016 IEEE 7th Annual Ubiquitous Computing, Electronics and Mobile Communication Conference, UEMCON 2016, 20 October 2016 through 22 October 2016 ; 2016 ; 9781509014965 (ISBN) ; Kaminska, B ; Akhavan, O ; Talebi, S ; Ghoranneviss, M ; Arab, Z ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
In this study, graphene sheets and carbon nanotubes (CNTs) were selectively grown on Fe foil at a relatively low growth temperature and varying cooling rates using a hot filament chemical vapor deposition (HFCVD) apparatus with C2H2 as the precursor. The results of the scanning electron microscopy and Raman spectroscopy revealed that the increase of the cooling rate from 7 to 10 or 20 °C/min provoked a structure transition from CNT to graphene. The optimum crystal quality of the graphene sheets (Iq/Id ∼1.1) was achieved at the cooling rate of 20 °C/min. According to the AFM analysis, the thickness of the stacked graphene sheets was found to be ∼2.9-3.8 nm containing ∼8-11 monolayers. The XRD...
A general two-step chemical vapor deposition procedure to synthesis highly crystalline transition metal dichalcogenides: a case study of MoS2
, Article Materials Research Bulletin ; Volume 76 , 2016 , Pages 473-478 ; 00255408 (ISSN) ; Vosoughi, M ; Maghsoudi, H ; Simchi, A ; Sharif University of Technology
Abstract
A green and simple synthesis method based on a two-step chemical vapor deposition approach has been developed to synthesize transition metal dichalcogenides flakes. With non-toxic precursor such as transition metal oxides and elemental sulfur, large-area, strong photoluminescent and uniform MoS2 nanoflakes were produced at a relatively low growth temperature (650 °C). Controlling the layer number and morphology was achieved only by precursor concentration without any oxide impurity revealed by SEM, PL and Raman spectroscopy. This method can be used to make wide range of metal chalcogenides such as ZnS, SnS2, PtS2 and PdS2
Developing seedless growth of atomically thin semiconductor layers: Application to transition metal dichalcogenides
, Article Ceramics International ; Volume 44, Issue 13 , 2018 , Pages 15795-15803 ; 02728842 (ISSN) ; Sovizi, S ; Ghanbari, H ; Simchi, A ; Aboudzadeh, N ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Controlled growth of atomic monolayers of IV-VII transition metal dichalcogenides (TMDs) has provided unprecedented opportunities to fabricate modern optoelectronic nanodevices. However, synthesis of large-area and high quality two-dimensional TMDs is still challenging. We have synthesized WS2 and MoS2 nanosheets by atmospheric pressure chemical vapor deposition (APCVD) at wide-range of processing conditions. The nanostructures were analyzed by optical and confocal microscopy, atomic force microscopy, Raman spectroscopy, and X-ray diffraction to determine the thickness, lateral size and structure of the deposits. Through designing and performing of a set of controlled experiments as well as...