Review of various gamma radiation dosimeters based on thin and thick films of metal oxides and polymer materials

This work reviews various thick and thin film radiation sensors made to date at University of Limerick. Numerous oxides such as NiO, LaFeO₃, CeO₂, TeO₂, In₂O₃, SiO₂, MnO etc. and their mixtures in different proportions were used. Polymers such as CuPc, NiPc, MnPc and CoPc were also studied in our laboratories. Thin and thick film devices were made in the form of resistor- and capacitor-type structures, structures with interdigitated electrodes, pn- junctions and transistors. The ⁶⁰Co and ¹³⁷Cs sources were used to expose the samples to radiation. Current-voltage characteristics, optical absorption spectra, Raman spectra, SEM, XRD measurements etc. for the samples were recorded after each exposure procedure and values of radiation damage were estimated. Mixing materials in different proportions was found to change the sensitivity of these devices. In general thin film devices were found to be more sensitive to lower doses of radiation than the counterpart the thick films. Properties of thick film devices were restored after annealing. This suggests that these films can be reused on repeatable basis. Thin film devices can hardly undergo heat treatment as diffusion of the materials occurs. It was experimentally demonstrated that it is possible to fabricate a device that would satisfy the requirement of particular application, such as the sensitivity to γ-radiation exposure and working dose region. Based on the above given data, these structures are therefore might be regarded as a cost-effective alternative for room temperature real time γ-radiation dosimetry.