Manganite-layer thickness-dependent photovoltaic effect of La0.9Sr0.1MnO3/SrNb0.01Ti0.99O3p–n heterojunction

The perovskite p–n heterojunctions were fabricated by depositing La0.9Sr0.1MnO3 (LSMO) layers with thicknesses ranging from 20 to 400 Å on SrNb0.01Ti0.99O3 (SNTO) single-crystal substrates by laser molecular beam epitaxy (laser-MBE). The open-circuit photovoltage of the LSMO/SNTO heterojunction at room temperature increases with the increase of the thickness of LSMO layer. This result is ascribed to the increase of the carrier amount and the enhancement of the built-in electric field in the space-charge region of the LSMO/SNTO heterojunction with the increase of the thickness of LSMO layer. Furthermore, we found that the speed of photovoltaic response is almost independent of the thickness of LSMO layer in the heterojunction.