高品質的單層石墨烯已成為材料科學領域的重要需求.石墨烯的合成主要透過化
學氣相沉積法在多晶銅箔上進行, 後續藉由轉移技術轉至各種基板。然而，合成高品質的
單層石墨烯極具挑戰性並需受到多種參數影響，包括溫度、壓力、氣體流量比例和生長時
間。本研究專注於優化石墨烯在多晶銅箔上的 氣相沉積法生長，以實現高品質、高均勻
性和高重複性。我們在兩種條件下研究這些參數的影響: 常壓下(760 torr)和低壓下(20-
40 torr), 以獲得高品質石墨烯合成的優化參數。
從初始合成溫度 1060°C 開始, 已成功將常壓氣相沈積法的合成溫度降低至
950°C，而低壓氣相沈積法則降至 930°C。在這兩種條件下合成的石墨烯均以濕式轉移的方
式，轉移至 SiO₂/Si 基板上，方便觀察與分析。透過光學顯微鏡和拉曼光譜分析，可觀察
到在常壓氣相沈積法的條件下多層石墨烯二次成核的面積比例下降，而在低壓氣相沈積法
的條件下幾乎完全形成單層石墨烯。同時，透過四點探針與霍爾效應量測電性分析, 針對
優化後的石墨烯, 其片電阻至約 900 Ω/sq、載子遷移率(mobility)範圍為 1000~1500
cm
2/V·s，而載子濃度(carries concentration)在兩種壓力條件下皆測得為 6~8 × 10¹²
/cm2。
依據上述優化多晶銅箔成長石墨烯的條件下，將低壓條件應用於單晶銅基板，
特別是 Cu(111)/藍寶石上。 Cu(111) 基板透過物理氣相沉積（ PVD）在藍寶石基底上生長，
以獲得平整,均勻的單晶表面，從而減少基板表面對石墨烯合成的影響。在 Cu(111)/藍寶
石上合成的石墨烯隨後以真空平壓貼合結合電化學剝離法轉移至 SiO₂/Si 基板上。
透過光學顯微鏡、掃描式電子顯微鏡和原子力顯微鏡分析顯示，所得石墨烯表
面高品質且均勻，無明顯缺陷（如皺摺、不平整或破裂） ;拉曼光譜進一步證實單層石墨
烯的高品質， ID/IG 比值低於 0.1， I2D/IG 比值介於 1.5–2 之間。本研究為 CVD 生長石墨
烯的品質與均勻性控制提供了更好的方法，推動其在未來電子應用中的發展。

High-quality single-layer graphene has become a critical need in the materials science industry.
Graphene synthesis is predominantly performed using chemical vapor deposition (CVD) on
polycrystalline Cu foils, followed by transfer onto various substrates. However, synthesizing highquality single-layer graphene is highly challenging and depends on several parameters, including
temperature, pressure, gas flow composition, and growth time. This study focuses on optimizing
the CVD growth of graphene on Cu to achieve high quality and reliability. We investigate the
influence of these parameters under two conditions: Atmospheric Pressure CVD (APCVD) and
Low-Pressure CVD (LPCVD), aiming to derive an optimized recipe for high-quality graphene
synthesis.
From the initial synthesis temperature of 1060°C, we successfully reduced the synthesis
temperature to 950°C under APCVD and 930°C under LPCVD. The resulting graphene in both
cases was wet-transferred onto SiO₂/Si wafers. Using optical microscopy (OM) and Raman
spectroscopy, we observed a significant reduction in multilayer graphene under APCVD conditions
and near-complete single-layer graphene formation under LPCVD. Furthermore, the graphene's
sheet resistance was optimized to approximately 800–1000 Ω/sq, as measured using a four-point
probe and Hall measurements. Carrier mobility values ranged from 1000–1500 cm²/V·s, and carrier
concentration was measured at 6–8 × 10¹²/cm² in both pressure conditions.
After optimizing the synthesis recipe for polycrystalline Cu foils, we applied the low-pressure
conditions to single-crystal Cu substrates, specifically Cu(111)/sapphire. The Cu(111) substrate
was grown on a sapphire base using Physical Vapor Deposition (PVD) to achieve a flat, uniform
single-crystal surface, minimizing surface-related effects on graphene synthesis. Graphene
synthesized on Cu(111)/sapphire was subsequently transferred onto SiO₂/Si wafers using Vacuum
Lamination (VL) combined with Electrochemical (EC).
OM, SEM, and AFM revealed a high-quality, uniform surface free from defects (wrinkles,
corrugations, or ruptures). Raman spectroscopy further confirmed the high quality of the singlelayer graphene, with an ID/IG ratio below 0.1 and an I2D/IG ratio of 1.5–2. This work paves the way
for better control over the quality and uniformity of CVD-grown graphene, advancing its potential
for future electronic applications

REFERENCE
1. Skoda, M., et al., Graphene: One Material, Many Possibilities—Application Difficulties in Biological Systems. Journal of Nanomaterials, 2014. 2014(1).
2. Bonaccorso, F., et al., Production and processing of graphene and 2d crystals. Materials Today, 2012. 15(12): p. 564-589.
3. Madurani, K.A., et al., Progress in Graphene Synthesis and its Application: History, Challenge and the Future Outlook for Research and Industry. ECS Journal of Solid State Science and Technology, 2020. 9(9).
4. Sharma, I., et al., Partial Pressure Assisted Growth of Single-Layer Graphene Grown by Low-Pressure Chemical Vapor Deposition: Implications for High-Performance Graphene FET Devices. ACS Omega, 2020. 5(35): p. 22109-22118.
5. Shin, Y.C., M.S. Dresselhaus, and J. Kong, Preparation of Graphene with Large Area, in Carbon Nanotubes and Graphene. 2014. p. 39-76.
6. Ago, H., CVD Growth of High-Quality Single-Layer Graphene, in Frontiers of Graphene and Carbon Nanotubes: Devices and Applications, K. Matsumoto, Editor. 2015, Springer Japan: Tokyo. p. 3-20.
7. Komlenok, M., et al., Crystallization of Copper Films on Sapphire Substrate for Large-Area Single-Crystal Graphene Growth. Nanomaterials (Basel), 2023. 13(10).
8. Ullah, Z., et al., A comparative study of graphene growth by APCVD, LPCVD and PECVD. Materials Research Express, 2018. 5(3).
9. Chaitoglou, S. and E. Bertran, Effect of temperature on graphene grown by chemical vapor deposition. Journal of Materials Science, 2017. 52(13): p. 8348-8356.
10. Lee, B., W. Chu, and W. Li, Effects of Process Parameters on Graphene Growth Via Low-Pressure Chemical Vapor Deposition. Journal of Micro and Nano-Manufacturing, 2020. 8(3).
11. Solution, T.T.K. What is the role of argon in CVD? Enhancing Purity, Stability, and Efficiency in Deposition Processes. 2024; Available from: https://kindle-tech.com/faqs/what-is-the-role-of-argon-in-cvd?srsltid=AfmBOooY7wps04zFnuqdIeOpQbpnjEgq64l0rS8ODbwNBeI-9P7WPUGq.
12. Ivan Vlassiouk, M.R., Pasquale Fulvio, Sheng Dai, Panos Datskos, Gyula Eres, Sergei Smirnov, Role of Hydrogen in Chemical Vapor Deposition Growth of Large SingleCrystal Graphene. ACS Nano, 2011. 5: p. 6069-6076.
13. Wenhua Zhang, P.W., Zhenyu Li, Jinlong Yang, First-principles thermodynamics of graphene growth on Cu surfaces. The Journal of Physical Chemistry C, 2011. 115(August 04, 2011): p. 17782-17787.
14. Yan, H., et al., Effect of staged methane flow on morphology and growth rate of graphene monolayer domains by low-pressure chemical vapor deposition. Thin Solid Films, 2021. 736.
15. A Jafari, R.A., M Ghoranneviss, The effects of growth time on the quality of graphene synthesized by LPCVD. Bulletin of Material Science, 2015. 38: p. 707-710.
16. Regmi, M., Chisholm, M. F., and Eres, G., The Effect of Growth Parameters on the Intrinsic Properties of Large-Area Single Layer Graphene Grown by Chemical Vapor Deposition on Cu. Carbon, 2012. 50: p. 134-141.
17. Xiao, K., et al., The study of the effects of cooling conditions on high quality graphene growth by the APCVD method. Nanoscale, 2013. 5(12): p. 5524-9.
18. Yu-Han, H., Study on the Fundamental Properties of Functionalized Graphene and Its Applications in Energy and Semiconductors, in Graduate Institute of Energy Engineering and Department of Mechanical Engineering. 2024, National Central University: NDEM lab.
19. Ibrahim, A., et al., Study of the impact of chemical etching on Cu surface morphology, graphene growth and transfer on SiO2/Si substrate. Carbon, 2017. 123: p. 402-414.