Manganese phthaloyanine polymer thick films were fabricated using screenprinting techniques. The optical parameters were obtained from the analysis of the absorption spectra over a wavelength range of 385-900nm. The d.c. electrical measurements were carried out in a range of 0-30 volts. The effects of γ-radiation on the optical and the electrical properties were investigated for dosimetry applications. The optical energy band gaps of these films showed a decrease in their values with the increase in the radiation dose. The electronic transition has changed from direct allowed for the as-printed films (unexposed to γ-rays) to indirect allowed for the irradiated samples. Both the as-printed and irradiated Ag/MnPc/Ag devices demonstrated a Schottky conduction mechanism. Both the absorbance and the capacitance of the MnPc thick films displayed a highly consistent linear response to γ-ray exposure.

Numerous efforts were devoted to investigating the influence of radiation on metal oxides and polymer materials for dosimetry applications. Metal oxides, such as NiO, LaFeO 3 , CeO 2 , TeO 2 , In 2 O 3 , SiO and MnO, and polymers, such as CuPc, NiPc, MnPc and CoPc, were used as the active constituents in the fabrication of -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 60 Co and 137 Cs sources were used to expose the samples to -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 -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 -radiation dosimeter applications.Index Terms-Gamma radiation, metal oxides, metal phthalocyanines, MOS, optical and electrical properties, personal dosimeter, pn-junction, thin and thick films.

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The dosimetry properties of thermally evaporated Copper Phthalocyanine (CuPc) thin films were investigated. The conduction mechanism of the asdeposited films was found to be space-charge-limited and their relative permittivity was within the range reported by others [l, 2, 3, 41. The Poole-Frenkel effect became more dominant for the irradiated samples and they displayed large increase in permittivity and colour centre density, although the energies of their optical band gap and trapping levels did not change. The observed linear relationship between the absorbance at 615 nrn and the y-radiation doses validated the use of CuPc as an optical sensor dosimeter especially for low radiation doses. Samples showed a higher radiation tolerance after being annealed for one hour at a temperature of only 323 K. Annealing also restored their initial electrical and optical properties.

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