Thick film oxide diode structures for personal dosimetry application

The aim of this work is to develop a novel sensor for gamma-ray radiation with instantaneous dosage readouts. Metal oxides, such as NiO, CeO2 and In2O3 are the key sensing elements in the proposed approach. The physical principles of radiation detection by oxide materials are connected with the radiation-induced formation of specific structural defects called colour centres. The density of these defects is dependent on the absorbed radiation dose. Thick film technology was used as it provides a reliable manufacturing of the radiation-sensitive layers with cost-effective mass production and good reproducibility. Polymer pastes of oxide materials were made of 92 wt.% of functional material and 8 wt.% of PVB, while ethylenglycolmonobutylether was used as a solvent. These polymer pastes were screen-printed on single side polished silicon wafers to form pn-junctions. Oxide materials that behave as p-type semiconductors were screen-printed on N(I 11) wafers, whereas n-type pastes were printed on P (10 0) silicon. All the devices were gradually exposed to a Cs-137 source. The I-V characteristics were measured at different doses. Results show that the current is increased with the increase in radiation dose to a certain level, which indicated the working dose region of the device. (C) 2004 Elsevier B.V. All rights reserved.