Simultaneous Etching and Doping by Cu-Stabilizing Agent for High-Performance Graphene-Based Transparent Electrodes

Abstract

Cu etching is one of the key processes to produce large-area graphene through chemical vapor deposition (CVD), which is needed to remove Cu catalysts and transfer graphene onto target substrates for further applications. However, the Cu etching method has been much less studied compared to doping or transfer processes despite its importance in producing higher quality graphene films. The Cu etchant generally includes a strong oxidizing agent that converts metallic Cu to Cu2+ in a short period of time. Sometimes, the highly concentrated Cu2+ causes a side reaction leading to defect formation on graphene, which needs to be suppressed for higher graphene quality. Here we report that the addition of metal-chelating agents such as benzimidazole (BI) to etching solution reduces the reactivity of Cu-etching solution by forming a coordination compound between BI and Cu2+. The resulting graphene film prepared by Cu stabilizing agent exhibits a sheet resistance as lows as ∼200 Ohm/sq without additional doping processes. We also confirmed that such strong doping effect is stable enough to last for more than 10 months under ambient conditions due to the barrier properties of graphene covering the BI dopants, in contrast to the poor stability of graphene additionally doped by strong p-dopant such as HAuCl4. Thus, we expect that this simultaneous doping and etching method would be very useful for simple and high-throughput production of large-area graphene electrodes with enhanced conductivity.

Broadband impedance match to two-dimensional materials in the terahertz domain

“…In order to achieve the necessary sheet conductance values near maximum absorption, and beyond ( Z 0 ) −1 , we utilized chemical (rather than electrical) tuning. We intentionally dope graphene films to have low sheet resistance in the zero-bias state (to mitigate inconsistencies that may arise from the inhomogeneous gating using a high-resistivity substrate, and to ensure no gate leakage occurs) by using benzimidazole (BI) dissolved into the copper etching solution during graphene transfer 31 (Supplementary Note 8 ). Figure 3f–h shows the broadband transmittance vs. frequency for three graphene films having zero-bias DC sheet resistances of 515, 373 and 250 Ω/□, respectively.…”

“…This process simultaneously etches the copper and dopes the graphene as described in ref. 31 . Following transfer, the wafer is dried overnight.…”

High-performance ultraviolet photodetectors based on solution-grown ZnS nanobelts sandwiched between graphene layers

“…Graphene is a single atomic layer consisting of carbon atoms arranged in a hexagonal honeycomb lattice, and it has been reported as one of the fascinating two-dimensional materials due to its outstanding physical properties including high mechanical flexibility 24 25 , electrical conductivity 26 27 28 29 , and transparency 30 . In addition, graphene has an excellent stability under ambient conditions due to its outstanding impermeability 31 32 33 . The incorporation of transparent and conductive graphene into photoactive semiconductors can be considered to provide synergistic effects in light absorption and carrier transportation.…”

33‐2: Flexible OLED Panels with Pixilated Graphene Anode

“…Monolayer graphene was grown on Cu foils using a chemical vapor deposition (CVD) method [11,12]. The sheet resistance of the four-layered graphene films was ~70 Ω/sq.…”