Dae Joon Kang
Sungkyunkwan University, Republic of Korea
Title: Graphene/h-BN heterostructures based field effect transistors employing chemical vapor deposition grown h-BN as a dielectric layer
Biography
Biography: Dae Joon Kang
Abstract
Hexagonal boron nitride (h-BN) has emerged as an exceptional dielectric material for graphene field effect transistors (GFETs). GFETs exploiting mechanically exfoliated h-BN dielectrics exhibited an order of magnitude improvement in device mobility, reduced carrier in-homogeneity, lower extrinsic doping, reduced chemical reactivity, and improved highbias performance when compared with devices with conventional oxide dielectrics. Chemical vapor deposition (CVD) based growth of high-quality graphene and h-BN over a large-area is currently the most widely used. However, the CVD grown h-BN dielectric has not been demonstrated for high-performance GFETs. This is mainly due to problems associated with a contamination issue in a thin poly(methyl methacrylate) (PMMA) assisted transfer of CVD-grown 2D materials, such as graphene and h-BN, from a growth substrate to a target substrate for the optical and electronic devices fabrication. This limits further study of heterostructure of 2D materials using layer-by-layer transferring methods. In this work, we have developed a facile transfer technique for 2D materials by adding a water-soluble PVA layer in-between PMMA and 2D materials grown on the rigid substrate. This technique allows not only effective transfer to a target substrate with a high degree of freedom but also etching-free PMMA-assisted transfer while minimizing the effects of related contaminants on the material surface. GFETs transferred by this process exhibits a negative shift of charge neutrality point close to zero and both graphene and graphene/h-BN FETs showed greater mobility, higher current modulation and smaller hysteretic than GFETs that use PMMA assisted transfer due to the elimination of PMMA contaminants. Our results demonstrated that the developed transfer method is so versatile that multilayer stacking of heterostructure of graphene and h-BN materials, and wafer-scale transfer are reliably performed. This facile transfer technique presents great potential for future research and application for high performance, flexible and transparent in the large area of mechanical, optical and electronic devices based on graphene/h-BN heterostructures.