Charge transport in Fe2O3 films deposited on nanowire arrays

The short diffusion length of photo-excited charge carriers in Fe2O3 is one of the factors limiting the water splitting efficiency of iron oxide based materials. To overcome this problem we are engineering transparent arrays of nanowires to act as conducting substrates for the Fe2O3. To help understand the charge transport characteristics of the Fe2O3 component we report transient photocurrent measurements performed on an absorbing thin film of Fe2O3 deposited by filtered arc deposition on conducting glass with a semi-transparent silver Schottky top contact. Ultraviolet laser pulses were used to generate charge carriers near the surface and the resulting current transients were measured. A simulation of this charge transport has also been developed. The sign of the observed transients was independent of applied bias, consistent with a fully depleted film. The measurements also suggest that recombination may play a significant factor in determining the transient shape. Further investigation is required to confidently predict mobilities.