Integration of Hexagonal Boron Nitride with Quasi-freestanding Epitaxial Graphene: Toward Wafer-Scale, High-Performance Devices

Abstract

Hexagonal boron nitride (h-BN) is a promising dielectric material for graphene-based electronic devices. Here we investigate the potential of h-BN gate dielectrics, grown by chemical vapor deposition (CVD), for integration with quasi-freestanding epitaxial graphene (QFEG). We discuss the large scale growth of h-BN on copper foil via a catalytic thermal CVD process and the subsequent transfer of h-BN to a 75 mm QFEG wafer. X-ray photoelectron spectroscopy (XPS) measurements confirm the absence of h-BN/graphitic domains and indicate that the film is chemically stable throughout the transfer process, while Raman spectroscopy indicates a 42% relaxation of compressive stress following removal of the copper substrate and subsequent transfer of h-BN to QFEG. Despite stress-induced wrinkling observed in the films, Hall effect measurements show little degradation (<10%) in carrier mobility for h-BN coated QFEG. Temperature dependent Hall measurements indicate little contribution from remote surface optical phonon scattering and suggest that, compared to HfO(2) based dielectrics, h-BN can be an excellent material for preserving electrical transport properties. Graphene transistors utilizing h-BN gates exhibit peak intrinsic cutoff frequencies >30 GHz (2.4× that of HfO(2)-based devices).

Raman study of damage extent in graphene nanostructures carved by high energy helium ion beam

“…In addition, suspended graphene devices are difficult to handle and are not suitable for many practical applications. On 3 the other hand, recent progress on the quasi-suspended graphene made by stacking with other 2-D materials has shown superior properties implying that a structural suspension may no longer be necessary for many high performance devices [20][21][22]. The mechanisms at play during the carving of suspended graphene and supported graphene can be very different owing to the complex interaction between ion/electron beams and the substrate material [23].…”

Generic miniband structure of graphene on a hexagonal substrate

“…In particular, we identify conditions at which the first moiré miniband is separated from the rest of the spectrum by either one or a group of three isolated mini Dirac points and is not obscured by dispersion surfaces coming from other minibands. In such cases the Hall coefficient exhibits two distinct alternations of its sign as a function of charge carrier density.PACS numbers: 73.22.Pr,73.21.Cd, Recently, it has been demonstrated that the electronic quality of graphene-based devices can be dramatically improved by placing graphene on an atomically flat crystal surface, such as hexagonal boron nitride (hBN) [1][2][3][4][5][6][7]. At the same time, graphene's electronic spectrum also becomes modified, acquiring a complex, energydependent form caused by incommensurability between the graphene and substrate crystal lattices [8][9][10].…”

Direct growth of large-area graphene and boron nitride heterostructures by a co-segregation method

“…To date, the growth of large-area graphene 11,12 and h-BN 13 on metal surfaces have been achieved by chemical vapour deposition (CVD) method. The graphene-on-h-BN (graphene/h-BN) or h-BN-on-graphene (h-BN/graphene) heterostructrues were obtained by stacking the CVD-grown graphene and h-BN on top of each other through the transfer process 14,15 . But the interfacial contamination is a big problem for the transfer approach, since the air, water 16 and hydrocarbon 8 can be easily trapped on surface.…”