Fabrication of Homogeneous Nanoporous Structure on 4H‐/6H‐SiC Wafer Surface via Efficient and Eco‐Friendly Electrolytic Plasma‐Assisted Chemical Etching
Shunda Zhan, Bowen Liu, Xuemeng Yu, Xihan Chen, Guosong Zeng, Yonghua Zhao
Abstract
Abstract Nanoporous single‐crystal silicon carbide (SiC) is widely used in various applications such as protein dialysis, as a catalyst support, and in photoanodes for photoelectrochemical water splitting. However, the fabrication of nano‐structured SiC is challenging owing to its extreme chemical and mechanical stability. This study demonstrates a highly‐efficient, open‐circuit electrolytic plasma‐assisted chemical etching (EPACE) method without aggressive fluorine‐containing reactants. The EPACE method enables the nano‐structuring of SiC via a plasma‐enveloped microtool traversing over the target material in an electrolyte bath. Through process design, EPACE readily produces a uniform nanoporous layer on a 4H‐SiC wafer in KOH aqueous solution, with adjustable pore diameters in the range 40–130 nm. Plasma diagnosis by optical emission spectrometry (OES) and surface microanalysis reveal that EPACE realizes a nanoporous structure by electrolytic plasma‐assisted oxidation and subsequent thermochemical reduction of an oxide. An increase in voltage or a decrease in etch gap intensifies the plasma and improves the etching efficiency. The maximum etch rate and depth reach 540 nm min −1 and 10 µm, respectively, demonstrating the significant potential of the approach as a time‐saving and sustainable nanofabrication method for industrial applications. Further, the effectiveness of the fabricated SiC nanoporous structure for application in photoelectrochemical water splitting is demonstrated.