Thin and thick films of metal oxides and metal phthalocyanines as gamma radiation dosimeters

Numerous efforts were devoted to investigating the influence of radiation on metal oxides and polymer materials for dosimetry applications. Metal oxides, such as NiO, LaFeO₃, CeO₂, TeO₂, In₂O₃, SiO and MnO, and polymers, such as CuPc, NiPc, MnPc and CoPc, were used as the active constituents in the fabrication of γ-radiation sensors. Thin and thick film devices were made in various topologies to form resistors, capacitors, pn-junctions and transistors. It was found that the properties of the active films (and, hence, their sensitivity to radiation) could be controlled by doping their constituent materials with carbon and mixing them in different proportions. The ⁶⁰Co and ¹³⁷Cs sources were used to expose the samples to γ-radiation. Current-voltage characteristics, optical absorption spectra, Raman spectra, SEM and XRD measurements were recorded for the samples after each exposure procedure and values of radiation damage were estimated. Thin film devices were found to be more sensitive to radiation than their thick film counterparts. Annealing was used to restore the properties of thick film devices after they were damaged with radiation. Thick films could be therefore reused on a repeatable basis, but thin film devices could not, as the heat treatments necessary for annealing were found to cause diffusion of the electrode materials. In this work, the possibility of fabricating a device that would satisfy the requirement of a particular application, such as sensitivity to γ-radiation and working dose region, was experimentally demonstrated. Based on the findings, these devices were found to provide a cost-effective alternative for room temperature real time γ-radiation dosimeter applications.