Enhanced photovoltaic currents in strained Fe-doped LiNbO sub(3) films

We investigate the impact of strain on photovoltaic current (J sub(z) characteristics for iron-doped LiNbO sub(3) (Fe-LN) under visible light illumination by thin-film experiments. The J sub(z)values are demonstrated to be dramatically enhanced for the film with a tensile strain along the P sub(s) direction, which is over 500 times as large as that of the bulk (strain-free) Fe-LN crystals. Density functional theory (DFT) calculations show that the tensile strain increases an off-center displacement of Fe super(2+) that is opposite to the P sub(s) direction. Our experimental and DFT study demonstrates that the control of the lattice strain is effective in enhancing the photovoltaic effect in the Fe-LN system.