Photovoltaic properties of BiFeO3 thin film capacitors by using Al-doped zinc oxide as top electrode

Abstract

We demonstrate using Al-doped zinc oxide films as electrode materials to form ferroelectric thin film capacitors. The photocurrent density and open circuit voltage for the capacitor with an Al-doped zinc oxide/BiFeO3/Fluorine doped tin oxide structure are measured to be 0.13mA/cm2 and 0.63V, respectively, much higher than the reported values for traditional BFO based capacitors. To clarify the contribution of Al-doped zinc oxide to the photovoltaic effect, Au top electrode was used as a comparison group. The Al-doped zinc oxide based capacitors show a more than 3 times larger photovoltaic output than that of the Au counterpart, which indicates that the Al-doped zinc oxide makes a major contribution to the high photovoltaic effect. The comparison shows that the larger photovoltaic effect may be attributed to the larger build-in-electric field, depolarization electric field and higher transparency of top electrode. Our results suggest that the transparent Al-doped zinc oxide film can be a promising electrode material in ferroelectric film capacitors and could be a potential replacement of indium tin oxide materials.