Direct observation of porous SiC formed by anodization in HF

Abstract

A process for forming porous SiC from single-crystal SiC wafers has been demonstrated. Porous SiC can be fabricated by anodizing n-type 6H-SiC in HF under UV illumination. Transmission electron microscopy reveals pores of sizes 10–30 nm with interpore spacings ranging from ≊5 to 150 nm. This is the first reported direct observation of porous SiC formation.

Photoelectrochemistry of 4H–SiC in KOH solutions

“…Photoanodic dissolution was observed for n-type material [10]. As in the case of Si [11,12], a mesoporous matrix could be formed by electrochemical etching [7]. Anodic etching was also used for patterning with the aid of photolithographic techniques and high etch rates were reported [8].…”

“…Shor and coworkers have carried out an extensive study of the photoelectrochemistry of SiC (b-SiC, 6H-SiC) in acidic fluoride solution [7][8][9]. The p-type material could be etched anodically in the dark [9].…”

Anodic etching of SiC in alkaline solutions

“…Photoanodic etching of ntype SiC in acidic fluoride solution has been investigated by Shor and co-workers. They showed that, depending on the experimental conditions, one can either obtain mesoporous or uniform etching [15,16]. The latter can be exploited for patterning of devices.…”

Large photocurrents in GaN porous structures with a redshift of the photoabsorption edge

“…Anodic porous etching on silicon and germanium was first reported by A. Uhlir at Bell Labs in 1956 [1]. After that, compound semiconductors such as GaAs [2,3], InP [4][5][6][7], GaP [8,9], GaN [10][11][12], and SiC [13] were studied. We have recently reported that InP and GaN porous structures show low photoreflectance and high photoabsorption [14][15][16], which are essential features of photoelectric and photochemical conversion devices such as solar cells and photoelectrodes.…”