Thinning Segregated Graphene Layers on High Carbon Solubility Substrates of Rhodium Foils by Tuning the Quenching Process

Abstract

We report the synthesis of large-scale uniform graphene films on high carbon solubility substrates of Rh foils for the first time using an ambient-pressure chemical vapor deposition method. We find that, by increasing the cooling rate in the growth process, the thickness of graphene can be tuned from multilayer to monolayer, resulting from the different segregation amount of carbon atoms from bulk to surface. The growth feature was characterized with scanning electron microscopy, Raman spectra, transmission electron microscopy, and scanning tunneling microscopy. We also find that bilayer or few-layer graphene prefers to stack deviating from the Bernal stacking geometry, with the formation of versatile moiré patterns. On the basis of these results, we put forward a segregation growth mechanism for graphene growth on Rh foils. Of particular importance, we propose that this randomly stacked few-layer graphene can be a model system for exploring some fantastic physical properties such as van Hove singularities.

All Chemical Vapor Deposition Synthesis and Intrinsic Bandgap Observation of MoS2/Graphene Heterostructures

“…[ 16,18,19 ] Otherwise, the controllable growth of Gr on various metal substrates and the related STM/STS analyses were also accomplished by our previous efforts. [29][30][31] Based on these, a direct all-CVD approach for synthesizing MoS 2 /Gr vertical heterostructures on Au foils is specifi cally designed, as illustrated in Figure 1 a. A nearly full coverage monolayer Gr fi lm was fi rst synthesized on Au foils by an atmospheric-pressure CVD route (using CH 4 precursor), and then, monolayer MoS 2 domains were deposited on Gr/Au via the low-pressure CVD method (using MoO 3 and S precursors).…”

Hierarchy of graphene wrinkles induced by thermal strain engineering

“…This wrinkling pattern is distinct from that of graphene flakes grown on solid Cu foils [30] and other solid metal substrates [31,32]. For graphene grown on solid metal surfaces, the directions of the wrinkles in different graphene flakes are of randomly distributed.…”

Understanding and strain-engineering wrinkle networks in supported graphene through simulations

“…Gas trapped between the graphene and the substrate, either unintentionally (Stolyarova et al, 2009;Georgiou et al, 2011) or in a controlled manner (Bunch et al, 2008;Koenig et al, 2011;Zabel et al, 2012;Pan et al, 2012;Kitt et al, 2013), can elastically deform graphene, producing blisters of various shapes and sizes. Lateral strain produced upon cooling of graphene grown by chemical vapor deposition (CVD) on solid metallic substrates invariably results in linear and localized wrinkles (Li et al, 2009;Robertson et al, 2011;Obraztsov et al, 2007;Zhu et al, 2012;Liu et al, 2012), which persist after transfer to other substrates. Similar wrinkles have also been reported in exfoliated flakes (Xu et al, 2009).…”

“…1(a). Most wrinkles observed in CVD graphene form two-dimensional networks (Li et al, 2009;Robertson et al, 2011;Obraztsov et al, 2007;Zhu et al, 2012;Liu et al, 2012), indicative of biaxial compressive strain and suggestive of stress focusing (Cerda et al, 1999;Witten, 2007;Pereira et al, 2010;Aoyanagi et al, 2010). Beyond isolated wrinkles, massive crumpling and delamination have been reported in supported multilayer graphene under very large biaxial compression (Zang et al, 2013).…”

“…It has been shown that the transfer process can increase, decrease, or even eliminate wrinkling Calado et al, 2012), and that wrinkles preferentially form at topographical features of the substrate (Kim, K. et al, 2011;Pan et al, 2011;Liu et al, 2012). However, it has not been possible to precisely and reversibly control the location of wrinkles, partly due to an insufficient theoretical understanding of wrinkling under biaxial compression .…”