Photoelectrochemistry of 4H–SiC in KOH solutions

Abstract

The photoelectrochemical oxidation of n-type 4H-SiC in KOH solution shows surprising features. While a limiting anodic photocurrent is observed at low light intensity, the semiconductor passivates at high intensity. The photocurrent corresponding to the passivation peak increases linearly with photon flux but decreases when mass transport in the system is enhanced. Characteristic current oscillations are observed. Possible reasons for these results are considered, as is the use of photoanodic etching for practical applications.

Influence of Electrochemical Etching on Electroluminescence from n-Type 4H- and 6H-SiC

“…Scratches are no longer visible; the surface shows microroughness. 16,17 After the removal of a thickness of 10.3 m of the surface layer, the emission spectrum changed considerably ͑Fig. 3͒.…”

SiC: A Photocathode for Water Splitting and Hydrogen Storage

“…[20,21] Electrochemical measurements were performed in a conventional three-electrode cell with a platinum counter electrode and a saturated calomel electrode (SCE) as reference. [20,21] UV light from a Hg arc-lamp (500W) was directed on to the sample using a dichroic mirror (280-400 nm) in combination with a planoconvex lens. The light intensity was varied with neutral-density filters.…”

“…The details of electrochemical etching of n-type and p-type SiC are published elsewhere. [20,21,28] Received: February 10, 2009 Published online: July 7, 2009 . Keywords: hydrogen · photoelectrochemistry · water splitting Figure 1.…”

“…In the vicinity of the flat-band potential, we see an anodic current due to dissolution of the semiconductor; this is followed by passivation. [20,21] These reactions depend on majority carriers: valence-band holes. The hysteresis in the return scan is due to oxide on the surface, which subsequently dissolves chemically.…”

SiC: A Photocathode for Water Splitting and Hydrogen Storage

“…In the vicinity of the flat‐band potential, we see an anodic current due to dissolution of the semiconductor; this is followed by passivation 20. 21 These reactions depend on majority carriers: valence‐band holes. The hysteresis in the return scan is due to oxide on the surface, which subsequently dissolves chemically.…”