Magnetron sputtering process of carbon-doped α-Fe2O3 thin films for photoelectrochemical water splitting

Thin films of alpha-Fe2O3 doped with carbon have been fabricated on F-doped SnO2 glass substrate by magnetron sputtering process via DC power on the pure Fe target (99.99%) combined with RF power on the pure graphite target (99.99%). The influences of RF power (0, 40, 80 and 120 W) on optical, structural and photoelectrochemical (PEC) characteristics have been investigated. The as-obtained samples after annealing in Ar ambient were analyzed by scanning electron microscopy, X-ray diffraction (XRD), Raman spectra, UV-visible spectra and electrochemical analysis. After annealing, all samples revealed only hematite characteristics in XRD pattern and Raman spectra. Thickness of annealed thin films was similar to 350 nm measured via SEM cross-section image. The optical band gap and carrier concentration of samples were in the range of 2.13-2.16 eV and 6.28 x 10(17) to 3.11 x 10(18) cm(-3), respectively. Based upon our observations, the 4.56 at.% carbon-doped alpha-Fe2O3 thin film deposited via 80 W RF power has a better PEC response with photocurrent density of similar to 1.18 mA/cm(2) at 0.6 V vs. SCE. This value was about three times higher than the un-doped film (0 W of RF power, reference sample). Observed higher photocurrent density was likely due to a suitable carbon-doping concentration causing a higher carrier concentration. (C) 2015 Elsevier B.V. All rights reserved.