Laser-induced voltages in unbiased YBCO-dependence on crystalline anisotropy

The photogenerated voltage in YBCO films without any current bias was studied by characterizing the grain orientations of the film samples and correlating them to the signal. Contradictory results to earlier reports were observed. It was found that crystal anisotropy was important in producing the photoinduced voltage. The photovoltaic response is ultimately related to the anisotropy of the lattice and can be used to study the crystal structure of these perovskites. The physics of this effect is quite different from the normal photoresponse under current bias. The latter is generally much stronger, and both thermal and nonthermal responses have been demonstrated