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A Rapid Thermal Chemical Vapor Deposition System for Fast Synthesis of Epitaxial Graphene Under Ambient Pressure

Shikhar Kumar Gupta, Meet Ghelani, Pragna Datta, Subhalakshmi Guha, Shivesh Yadav, Nilesh Kulkarni, Maheshwar Gokhale, Bhagyashree Chalke, Devendra Buddhikot, Naveen Paneri, Lavudya Devendar, Arnab Bhattacharya, Shouvik Chatterjee

TL;DR

Addresses the need for scalable, high-quality graphene synthesis at atmospheric pressure. Introduces a compact halogen-lamp based RTCVD system operating as a cold-wall CVD, enabling growth of epitaxial graphene on Cu(111) templates with turnaround times under $25$ minutes and a temperature ramp rate exceeding $23^\circ\mathrm{C}/\mathrm{s}$. Raman, SAED, and magnetotransport measurements confirm predominantly monolayer, single-crystalline graphene exhibiting half-integer quantum Hall effect, with mobilities up to about $6{-}7\times10^3\ \mathrm{cm^2/Vs}$ at 2 K; transfer to Si/SiO$_2$ substrates and van der Waals epitaxy of Pd on graphene demonstrate the material's versatility as a large-area template. The results position RTCVD as a fast, cost-effective pathway for scalable graphene production and heteroepitaxial integration on graphene.

Abstract

Graphene has emerged as a promising material for next-generation electronic and thermal devices owing to its exceptional charge transport and thermal conductivity. However, high-quality samples are predominantly obtained via mechanical exfoliation from graphite crystals, a process that inherently lacks scalability. Despite extensive efforts toward large-area synthesis, cost-effective approaches for producing high-quality, large-area, single-crystalline graphene with fast turnaround time remain limited. Here, we report the design, fabrication, and performance benchmarking of a rapid thermal chemical vapor deposition (RTCVD) system capable of synthesizing epitaxial monolayer graphene under atmospheric pressure. The entire growth process, from sample loading to unloading, is achieved within $25$ minutes with a temperature ramp rate exceeding $23^\circ\mathrm{C}/s$. Growth at atmospheric pressure eliminates the need for vacuum components, thereby reducing both system complexity and operational costs. The structural and electronic quality of epitaxial graphene is comprehensively characterized using Raman spectroscopy, selected area electron diffraction (SAED), and magnetotransport measurements, which reveal signatures of quantum Hall effect in synthesized graphene samples. Furthermore, we demonstrate van der Waals epitaxial growth of palladium (Pd) thin films on graphene transferred to Si/SiO$_{2}$ substrates, establishing its single-crystalline nature over a large area and its potential as a versatile platform for subsequent heteroepitaxial growth.

A Rapid Thermal Chemical Vapor Deposition System for Fast Synthesis of Epitaxial Graphene Under Ambient Pressure

TL;DR

Addresses the need for scalable, high-quality graphene synthesis at atmospheric pressure. Introduces a compact halogen-lamp based RTCVD system operating as a cold-wall CVD, enabling growth of epitaxial graphene on Cu(111) templates with turnaround times under minutes and a temperature ramp rate exceeding . Raman, SAED, and magnetotransport measurements confirm predominantly monolayer, single-crystalline graphene exhibiting half-integer quantum Hall effect, with mobilities up to about at 2 K; transfer to Si/SiO substrates and van der Waals epitaxy of Pd on graphene demonstrate the material's versatility as a large-area template. The results position RTCVD as a fast, cost-effective pathway for scalable graphene production and heteroepitaxial integration on graphene.

Abstract

Graphene has emerged as a promising material for next-generation electronic and thermal devices owing to its exceptional charge transport and thermal conductivity. However, high-quality samples are predominantly obtained via mechanical exfoliation from graphite crystals, a process that inherently lacks scalability. Despite extensive efforts toward large-area synthesis, cost-effective approaches for producing high-quality, large-area, single-crystalline graphene with fast turnaround time remain limited. Here, we report the design, fabrication, and performance benchmarking of a rapid thermal chemical vapor deposition (RTCVD) system capable of synthesizing epitaxial monolayer graphene under atmospheric pressure. The entire growth process, from sample loading to unloading, is achieved within minutes with a temperature ramp rate exceeding . Growth at atmospheric pressure eliminates the need for vacuum components, thereby reducing both system complexity and operational costs. The structural and electronic quality of epitaxial graphene is comprehensively characterized using Raman spectroscopy, selected area electron diffraction (SAED), and magnetotransport measurements, which reveal signatures of quantum Hall effect in synthesized graphene samples. Furthermore, we demonstrate van der Waals epitaxial growth of palladium (Pd) thin films on graphene transferred to Si/SiO substrates, establishing its single-crystalline nature over a large area and its potential as a versatile platform for subsequent heteroepitaxial growth.

Paper Structure

This paper contains 4 sections, 7 figures.

Table of Contents

  1. Introduction
  2. Design and Working Principle
  3. Growth Condition and Characterization
  4. Conclusion

Figures (7)

  • Figure 1: (a) Front view and (b) top view of the RTCVD setup. (c) The sample loader assembly consisting of a smaller quartz tube with the graphite block, along with Cu foil on top (d) Cross-sectional view of the sample loader showing the position of the thermocouple. (e) An image of the RTCVD setup (f) Lamp holder assembly. All the individual components of the RTCVD setup are shown with an arrow: (A) sample loader (B) larger quartz tube (C) halogen Lamp (D) connector (E) housing for Al reflector (F) fan (G) gas inlet (H) gas outlet (I) Cu foil (J) graphite block (K) smaller quartz tube (L) KF40 connector (M) Wilson seal (M1) inner thread (M2) Al ring (M3) viton O-ring (M4) KF connector (N) thermocouple (O) cooling lines connected to chiller. (P) SS plates (Q) screw rods (R) Wilson seal coupler (S) KF40 coupler.
  • Figure 2: (a) AFM image of 1 $\mu$m thick Cu film before graphene growth. RMS roughness is 1.6 nm over 5 x 5 $\mu m^{2}$. (b) Pole figure of Cu (002) plane showing 6 fold symmetry due to the presence of twins on the Cu (111) surface (c) Out-of-plane $\theta-2\theta$ scan of Cu establishing the presence of only ($lll$) diffraction planes. Substrate peaks are marked by asterisks. (b) and (c) establish the epitaxial nature of Cu thin films. Inset show rocking curve of Cu (111) diffraction peak with a FWHM of 0.13$^\circ$.
  • Figure 3: Temperature profile of graphene growth in RTCVD
  • Figure 4: (a) Raman spectrum obtained after averaging over a $150\times150~\mu\mathrm{m}^2$ area using a $50\times50$ grid, taken from graphene transferred to Si/SiO$_{2}$ substrate, showing the characteristic $G$, $2D$, and the defect $D$ peaks. Inset shows an optical image of the graphene transferred to Si/SiO$_{2}$ substrate on which Raman spectroscopy was done. Raman maps showing the distribution of (b) intensity ratio of the $2D$ and $G$ peaks - $I_{2D}/I_{G}$ (d) intensity ratio of the $D$ and $G$ peaks - $I_{D}/I_{G}$ and (f) FWHM of the $2D$ peak over a $150 \times 150~\mu\mathrm{m}^2$ field of view. Corresponding histogram plots are shown in (c), (e), and (g), respectively.
  • Figure 5: (a) Regions where SAED measurements were performed, the square represents the position where the reference image was taken, as discussed in the main text. (b) Distribution of the relative orientation angles calculated from SAED images at different regions with respect to the reference image. Representative SAED images taken at two different regions marked with (c) a triangle and (d) a pentagon, respectively, in (a).
  • ...and 2 more figures