Carbon nanowalls (CNWs), which are used as electrodes for secondary batteries in energy storage systems (ESSs), have the widest reaction surface area among the carbon-based nanomaterials, but their application is rare due to their low adhesion with substrates. Indium tin oxide (ITO), a representative transparent conducting oxide (TCO) material, is widely used as the electrode for displays, solar cells, etc. Titanium nitride (TiN) is a well-used material as an interlayer for improving the adhesion between two materials. In this study, ITO or TiN thin films were used as an interlayer to improve the adhesion between a CNW and a substrate. The interlayer was deposited on the substrate using a radio frequency (RF) magnetron sputtering system with a four-inch TiN or ITO target. CNWs were grown on the interlayer-coated substrate using a microwave-plasma-enhanced chemical vapor deposition (MPECVD) system with a mixture of methane (CH₄) and hydrogen (H₂) gases. The adhesion of the CNW/interlayer/substrate structure was observed through ultrasonic cleaning.

The application of a carbon nanowall (CNW) via transfer is very demanding due to the unusual structure of vertically grown wall-shaped that easily collapses. In addition, direct growth on a device cannot obtain a precision-patterned shape because of the temperature limit of the photoresist (PR). Therefore, in this paper, we demonstrate a new CNW surface micromachining technology capable of direct growth. In order to reduce unexpected damage caused by chemical etching, a physical force was used to etch with the adhesive properties of CNWs that have low adhesion to silicon wafer. To prevent compositing with PR, the CNW was surface modified using oxygen plasma. Since there is a risk of surface-modified CNW (SMCNW) collapse in an ultrasonic treatment, which is a physical force, the CNW was coated with PR. After etching the SMCNW grown on PR uncoated area, PR was lifted off using an acetone solution. The effect on the SMCNW by the lift-off process was investigated. The surface, chemical, and structural properties of PR-removed SMCNW and pristine-SMCNW were compared and showed a minimal difference. Therefore, the CNW surface micromachining technique was considered successful.

In this study, several characteristics of carbon oxide nanowalls (CONWs) and reduced-carbon-oxide nanowalls (rCONWs) activated using plasma and thermochemistry were investigated. To become modified CONW and rCONW, catalyst-free carbon nanowalls (CNWs) were grown on a silicon (Si) wafer via microwave-plasma-enhanced chemical vapor deposition (MPECVD) with a mixture of hydrogen (H₂) and methane (CH₄) gases. The CONW was modified by oxidizing a CNW on a Si wafer with plasma treatment using oxygen (O₂) plasma. Afterwards, the CONW was placed in a rapid-thermal-annealing (RTA) chamber, and H₂ gas was injected thereto; therefore, the CONW was reduced by H₂ gas. The surface properties of the CONW and rCONW were confirmed via scanning electron microscopy (SEM). Raman spectroscopy was used for structural analysis, and the surface energy of each surface was analyzed by operating the contact angle. The chemical characteristics were observed via X-ray photoelectron spectroscopy (XPS). Hall measurements were applied to investigate the electrical characteristics.