Synthesis and Optimization of CVD grown Graphene for Improved Drop Wise Condensation

  • Sohail Shah

Student thesis: Master's Thesis

Abstract

The mechanism of graphene growth by Chemical Vapor Deposition is critical for synthesis of high quality graphene. Out of the many process parameters involved in graphene growth, the effect of H2 concentration during annealing stage is thought to have a major impact on nucleation and growth of graphene domains. Interestingly, there are different theories and results obtained on the study of annealing time and H2 concentration. In this present work, we investigated the effect of H2 concentration on the surface morphology of copper substrate as well as the graphene synthesized on it. Our results reveal that increasing H2 concentrations definitely has an improved effect on the quality of graphene growth due to change in surface morphology of the copper substrate. Surface striation lines were reduced considerably as the annealing time was increased from 15 minutes to 45 minutes. Low H2 concentrations (2.5% and 15%) resulted in multi-layer non-uniform and highly defective graphene growth due to rough copper surface comprising of surface dents, highly oriented facets and nanoparticles which act as active nucleation sites. In contrast, high H2 concentration during annealing promoted high quality uniform growth of monolayer and bilayer graphene. Also, many domains were stitched together to form lesser domains but covering larger area of the copper surface for higher H2 concentration used. Moreover, condensation experiments were carried out to study the effect of in situ grown graphene as opposed to transferred graphene on drop wise condensation. In situ grown graphene by CVD technique allowed drop wise condensation and contact angle as high as 118°. In contrast, graphene transferred onto copper surface yielded many defects like wrinkles and tears due to which the underlying substrate was exposed yielding high thermal resistance and flooding issues respectively.
Date of AwardDec 2016
Original languageAmerican English
SupervisorAmal Al Ghaferi (Supervisor)

Keywords

  • Chemical Vapor Deposition
  • Graphene
  • Graphene Oxide
  • Mechanical Exfoliation
  • Chemical Exfoliation
  • Raman Spectroscopy
  • Electron Microscope
  • Quanta 250
  • Nova Nano SEM
  • Topographic.

Cite this

'