Shanghai Institute of Microsystem and Information Technology, CAS
On the long journey towards graphene based electronics: from single crystalline graphene wafer to edge controlled graphene nanoribbon
Tianru WU, Haomin WANG, Xiaoming XIE*
State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
Can graphene eventually play a role in scalable electronics application? There are a number of technical barriers to overcome. These barriers include a suitable dielectric substrate which can preserve graphene’s superior properties, the ability to fabricate wafer-scale single crystalline graphene wafer either by direct deposition or by transferring the as produced graphene wafer to the dielectric substrate with tolerable defect level, the ability to create a band gap and to control the p/n type conduction etc. In this talk, I will present the latest progresses at our institute along the long journey towards graphene’s electronics applications. By introducing carbon precursor locally on the Cu85Ni15 alloy with moderate carbon solubility, we succeed in creating one single nucleus on the wafer-sized substrate. Single nucleus regime was maintained during the growth period, following a new isothermal segregation mechanism. Carbon stored in the substrate accelerates the growth, yielding in a 1.5 inch monolayer single crystalline wafer in only 2.5 hours. Growth of AB-stacked graphene was demonstrated by encaging Cu85Ni15 substrate with copper foils. The synergic effects of Cu85Ni15 and copper vapor evaporated from copper foil yield a fast growth of ~ 300 mm bilayer graphene in ~10 minutes. The copper vapor reduces the growth rate of the first layer of graphene while the carbon dissolved in the alloy boosts the growth of the subsequently developed second graphene layer with AB-stacking order. The success lies mainly in the largely reduced disparity of growth rates of the first and the second layer, one of the major reasons preventing the fast growth of large-domain-sized AB-stacked bilayer graphene. The edge controlled graphene nanoribbon was realized by templated-growth diretly on single crystalline hBN flakes, where nano-trenches in monolayered depth were produced by nickel particle assisted etching. The nano-trenches can be controlled to be mainly along zigzag or armchair directions allowing for in-plane epitaxy of graphene. Field effect transitor made with sub-10 nm graphene nano-ribbons showed transport band gap larger than 0.3 eV and on/off ratio greater than 103, pointing to a possile way towards graphene based digital electronics. Results on the synthesis of mono-layer and multilayer hBN will also be briefly presented, as our long term goal for single crystalline graphene wafer on wafer-sized single crystalline hBN substrate. With the encouraging progresses, we can envisage a good potentiality for graphene in electronics application, although there are still formidable challenges ahead.
1. T. Wu, et al. Fast growth of inch-sized single-crystalline graphene from a controlled single nucleus on Cu-Ni alloys. Nature Materials, 15, 43-47 (2016).
2. C. Yang, et al., Copper-Vapor-Assisted Rapid Synthesis of Large AB-Stacked Bilayer Graphene Domains on Cu-Ni Alloy, Small, DOI: 10.1002/smll.201503658 (2016).
L. Chen, et al, Oriented graphene nanoribbons embedded in hexagonal boron nitride trenches, Nature Communications, 8, 14703，DOI: 10.1038/ncomms14703 (2017).
Xiaoming XIE received his B.S. degree from Wuhan University in 1985, majoring in metal physics. He received his Ph.D degree in 1990 in Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences (SIMIT-CAS) with his thesis work on the investigations of microstructures of cuprate superconductors. He worked in the team of Surface et Supraconducteur in Ecole Superrieure de Physique et de Chimie Industrielles de la ville de Paris (ESPCI), France as a visiting scholar from March 1993 to November 1995. From 1995 to 2005, he switched to electronics materials and electronics packaging. He established the SIMIT’s research teams on graphene and on superconducting electronics. His main research interests include two-dimensional quantum materials, superconducting materials and hetero-structures, development of superconducting devices and applications. He contributed to ~ 200 publications in scientific journals with ~2000 citations and filed 165 patents, among which 67 was granted.