Photovoltaic response map in PUT ceramics doped with various impurity elements

摘要

It is widely known as the anomalous photovoltaic effect (APE) that a voltage which considerably exceeds band gap energies can be generated in uniform noncentrosynimetric materials upon homogeneous illumination in the absence of external fields [1]. The photovoltage reaches the order of kilovolts to megavolts per centimetre in certain ferroelectrics to make the APE not only of interest theoretically but also of practical importance. As promising applications of the APE, several novel devices such as photostrictors, all-optical control modulators and deflectors have been proposed recently [2-7]. In those reports studies were focused mostly on improvement of the photovoltaic response, which is considered as one of the most significant problems for practical usage. Tanimura and Uchino previously examined impurity doping effects on the APE in lead lanthanum zirconate titanate (PLZT) ceramics [3]. They found that the APE was increased by doping of donor ions such as Ta~(5+) and W~(6+). Except for this result, however, no clear relation between the kind of doped ions and the APE was recognized. Control of the photovoltaic response will also become important in future to obtain different characteristics to suit individual requirements in specific applications, as is now very commonly seen in other electronic materials.