Abstract
During selective growth of graphene by using silicon dioxide (SiO2) patterns on Cu foil (SOCF), multilayer graphene was grown on SOCF under the same conditions that are used to synthesize single-layer graphene (SLG) on blank Cu foil. The authors demonstrated that oxygen (O2) species that can be released from the SiO2 film did not affect the layer increase and that the SiO2 film of SOCF reduced the area of the exposed Cu surface and thereby increased the relative concentration of hydrogen (H2) to the Cu surface and initially grown graphene; as a result, extra graphene layers grew on SOCF. By adjusting the H2 supply and SiO2 coverage, uniformly-grown SLG patterns were obtained on SOCF. A damage-free graphene field effect transistor (GFET) was fabricated using selectively-grown SLG and direct transfer using parylene-C. The field effect mobility of the GFET was 7538.81 cm2/(V s), which is quite high compared to those of chemical vapor deposition based GFETs on flexible substrates that have been reported.
Highlights
Graphene has remarkable properties, such as high carrier mobility, electrical conductivity, transparency, elasticity, and chemical resistance, so it has many possible applications in electronic devices.1–4 Graphene field effect transistors (GFETs) are promising electron devices in flexible electronics because of their high carrier mobility and excellent mechanical flexibility.5–7 Graphene is generally synthesized as a bulk film on metal catalyst by chemical vapor deposition (CVD),8 so subsequent patterning by postgrowth lithography is required to obtain shaped graphene films for use in electronics
multilayer graphene was grown on SOCF under the same conditions
The authors demonstrated that oxygen
Summary
Graphene has remarkable properties, such as high carrier mobility, electrical conductivity, transparency, elasticity, and chemical resistance, so it has many possible applications in electronic devices. Graphene field effect transistors (GFETs) are promising electron devices in flexible electronics because of their high carrier mobility and excellent mechanical flexibility. Graphene is generally synthesized as a bulk film on metal catalyst by chemical vapor deposition (CVD), so subsequent patterning by postgrowth lithography is required to obtain shaped graphene films for use in electronics. We identified the conditions to produce uniform SLG in selective growth using silicon dioxide (SiO2) patterns on Cu foil (SOCF) and fabricated a damage-free GFET by using a combination of selective growth and direct transfer to minimize the degradation of graphene’s carrier mobility during device fabrications. To achieve high mobility of GFETs on a flexible substrate, we fabricated a GFET based on this SLG combining a direct transfer using parylene-C. The combination of selective growth and direct transfer avoided the damage that graphene can suffer during conventional patterning and transfer and yielded a flexible GFET that has high carrier mobility. After selective growth of the graphene pattern, the SiO2 pattern was removed in 10:1 BOE and a 5-μm-thick parylene-C was deposited directly on the graphene pattern on Cu foil by CVD. Gate dielectric ( parylene-C, 300 nm) and gate electrode (Au, 50 nm) were fabricated in the same way of the substrate and source/drain electrodes formation
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