Fabrication of p-Type La: Fe2O3 as Photocathode Via Atomic Layer Deposition

Abstract

P-type La: Fe2O3 and the n-p junction of Fe2O3/La: Fe2O3 have been fabricated by ALD technique for its excellent conformability and controllable film growth with low defect densities. La: Fe2O3 film is demonstrated with p-type characteristics by Mott−Schottky plots and the hole concentration is calculated ~ 1.97 × 1015 cm-3. It also obtains a cathodic photocurrent ~28 μA/cm2 at -0.8 V vs. Ag/AgCl. When forming the n-p junction of Fe2O3/La: Fe2O3, it is found that the onset potentialexhibits a negative shift of ~150 mV and the photocurrent densities increases from 0.62 mA/cm2 to 1.31 mA/cm2 at 0.5 V vs. Ag/AgCl. Generally, the incident photon-to-current conversion efficiency (IPCE) of Fe2O3/La: Fe2O3 n-p junction reaches ~4.47% at 400 nm. Our results imply that it is desirable to tune the energy mismatch between water splitting potentials and the band edges of Fe2O3 by a facile surface modification by forming a solid n-p junction.