Growth of Millimeter-Sized Graphene Single Crystals on Al₂O₃(0001)/Pt(111) Template Wafers Using Chemical Vapor Deposition

Abstract

The synthesis of graphene using chemical vapor deposition on platinum surfaces is discussed. The crystalline nature of the platinum substrates as well as the graphene growth conditions play a key role to yield monolayer graphene with low defectivity. The need for template wafers with a single Pt orientation emerges due to graphene overgrowth on untextured polycrystalline Pt foils. Singlecrystalline Pt foils can be obtained after long annealing steps. However, these Pt foils remain rough and are therefore less suitable during subsequent graphene transfer procedures. On the other hand, highly oriented platinum thin films avoid the overgrowth issues but result in differing nucleation phenomena on different oriented grains. An optimized graphene growth template is found in Al 2 O 3 (0001)/Pt(111), which is more than one order of magnitude flatter compared to the annealed Pt(111) foils and serves as an ideal catalyst to grow graphene grains exceeding 7 mm in diameter.

Spin communication over 30 µ m long channels of chemical vapor deposited graphene on SiO 2

“…Pairs of these contacts are used as spin injector and spin detector while their separation defines the spin channel length L. We systematically studied the fabrication of the devices to optimize their quality in terms of the graphene source, electron-beam resists, and post-fabrication processing. The raw graphene in the optimized devices was grown on Pt foils at temperatures up to 1100 o C by CVD [8]. It was then transferred using electrochemical methods with tetraethyl ammonium hydroxide (0.1M) as electrolyte solution that allow ~100% coverage with good adhesion on SiO 2 /Si (with 90 nm thick oxide layer) substrates [10], [11].…”

“…In this study, we demonstrate a high-yield fabrication of non-local lateral spin devices with long-distance spin transport at room temperature. The devices are patterned on platinum-based chemical vapor deposition (Pt-CVD) synthesized single-layer graphene on SiO 2 /Si substrates [8]. We present structural and spin transport characterization of devices with channel lengths L varying from 4 to 30 µm.…”

Substrate Engineering for CVD Growth of Single Crystal Graphene

“…To solve this problem, a highly flat Pt(111)/sapphire substrate was employed. [ 69 ] Pt(111) film with a thickness of 500 nm was e‐beam evaporated onto a single crystal sapphire substrate at a deposition rate of 0.1 nm s −1 followed by annealing. By tuning the growth temperature at an optimized gas flow of CH 4 and H 2 (6 sccm:850 sccm), SCG >7 mm was obtained (Figure 3k,l).…”

Direct Wafer-Scale CVD Graphene Growth under Platinum Thin-Films

“…When graphene is grown on Cu or Ni foils, the foil is often etched away after the growth process. However, Pt foils are costly, and reuse of the foils is therefore often preferred, which has led to the development of processes to delaminate the graphene from the Pt surface [ 24 ], or grow it on much thinner Pt layers [ 25 ]. Growth on Pt can thus yield high-quality graphene, if the transfer challenges discussed in Section 1.1 can be dealt with.…”