Neeraj Mishra: Going beyond copper - wafer-scale synthesis of graphene on sapphire

N. Mishra1,2, S. Forti1, F. Fabbri1,2, L. Martini1, C. McAleese3, B. Conran3, P.R. Whelan4,5, A. Shivayogimath4,5, Lars Buß6, Jens Falta6, I. Aliaj7, S. Roddaro7,8, J. I. Flege6,9, P. Bøggild4,5, K.B.K. Teo3 and C. Coletti1,2,* 1Center for Nanotechnology Innovation @ NEST, Istituto Italiano di Tecnologia , Piazza San Silvestro 12,56127 Pisa, Italy 2Graphene Labs, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy 3AIXTRON Ltd., Buckingway Business Park, Anderson Rd, Swavesey, Cambridge CB24 4FQ, UK 4DTU Physics, Ørsteds Plads 345C, 2800 Kgs. Lyngby, Denmark 5Center for Nanostructured Graphene (CNG), Ørsteds Plads 345C, 2800 Kgs. Lyngby, Denmark 6Institute of Solid State Physics, University of Bremen, Bremen-28334, Germany 7NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza S. Silvestro 12, I-56127 Pisa, Italy 8Dipartimento di Fisica, Università di Pisa, Largo B. Pontecorvo 3, 56127, Pisa (PI), Italy 9Brandenburg University of Technology Cottbus-Senftenberg, Chair of Applied Physics and Semiconductor Spectroscopy, Konrad-Zuse-Str. 1, 03046 Cottbus, Germany The adoption of graphene in electronics, optoelectronics and photonics is hindered by the difficulty in obtaining high quality material on technologically relevant substrates, over wafer-scale sizes and with metal contamination levels compatible with industrial requirements. To date, the direct growth of graphene on insulating substrates has proved to be challenging, usually requiring metal-catalysts or yielding defective graphene. In this work, we demonstrate a metal-free approach implemented in commercially available reactors to obtain high-quality monolayer graphene on c-plane sapphire substrates via chemical vapour deposition (CVD). We identify via low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) measurements the Al-rich reconstruction (√31×√31)𝑅±9° of sapphire to be crucial for obtaining high-quality graphene. Raman spectroscopy and electrical transport measurements reveal high quality graphene with mobilities consistently above 2000 cm2/Vs. We scale up the process to 4-inch and 6-inch wafer sizes and demonstrate that metal contamination levels are within the limits for back-end-of-line (BEOL) integration. The growth process introduced here establishes a method for the synthesis of wafer-scale graphene films on a technologically viable basis. [1] N. Mishra, et al., arxiv (2019). [2] M. A. Fanton, et al., ACS Nano (2011). [3] J. Hwang, et al., ACS Nano (2013). Neeraj Mishra is a post-doctoral fellow in 2D material engineering group of Dr. Camilla Coletti in Istituto Italiano di Tecnologia (IIT), Pisa, Italy. His main work is the growth of Graphene on insulators like h-BN and sapphire by the CVD method and its characterization. Besides, he has experience of the growth of Graphene on copper and different technique of Gr transfer. He has highly experienced with chemical vapor deposition using different growth systems including Aixtron-BM and characterization techniques such as scanning tunneling microscopy, Atomic force microscopy, and Raman spectroscopy. During his Ph.D. has experience of growth SWCNTs and MWCNTs from waste plastics. He has completed his Ph.D. under the guidance of Prof. Maheshwar Sharon and worked on the project of University Grant Commission (UGC) title entitled “Scaling up of conversion technology of waste plastics into CNM and burnable Wax”. During the Ph.D. program, he was selected for MIUR scholarship in Soft Material Design Laboratory, Istituto Italiano di Tecnologia (IIT), Genova, Italy on a project entitled “Transparent carbon nanotubes conductive networks for flexible electronics and polymer solar cell technology” in the year 2010. He has done his Bachelor (B.Sc. in Chemistry), M.Sc. (Physical chemistry) and Ph.D. in chemistry from the University of Mumbai. He has several papers in good journals.