Growth of potassium tantalate dielectric crystals and their application as photovoltaic UV detectors

Large single crystals (.5 \times .5 \times 4cm) of KTaO3have been grown by the Czochralski method. The growth parameters and electrical properties have been investigated. Crystals were grown either highly insulating (>10^{14}\Omega) or semiconducting n-type depending upon growth conditions. Photovoltaic cells were made by contacting the KTaO3with either evaporated thin metal films or silver paint. The ultraviolet (UV) responsivity and detectivity of an a.c. photovoltaic cell using KTaO3has been measured. Under no-bias conditions the responsibity was7.0 \times 10^{6}V/W and the detectivity, Dλ^*, was\sim 10^{12}cm Hz^1/2/W at 3000Å measured a t 20 Hz. Other properties are also discussed.