Enhanced Photocurrent in Rh-Substituted α-Fe2O3 Thin Films Grown by Pulsed Laser Deposition

Rh-substituted alpha-Fe2O3 (Fe(2-x)RhxO(3); 0.0 <= x <= 2.0) thin films were grown on alpha-Al2O3(110) substrates with a Ta-doped SnO2 electrode layer by pulsed laser deposition. Highly oriented epitaxial films with pure corundum structures were successfully fabricated over the entire compositional range. The optical absorption spectra of the films indicate narrowing of the bandgap with increasing Rh content. Consequently, the photoelectrochemical performance was improved in the Rh-substituted films. We found that the optimum Rh content lies at around x = 0.2, where the photocurrent is significantly enhanced over a wavelength range of 340-850 nm. (C) 2012 The Japan Society of Applied Physics