A comparative study of the radiation dose response of (ZnO)x(TeO2)1-x thin films for high energy X-ray application

Abstract

The current research work determines the X-ray radiation effects on the current–voltage (I-V) characteristics of zinc oxide-doped tellurium dioxide thin film as a dosimetric material for X-ray detection and measurement. Five thin-film samples of (ZnO)x(TeO2)1-x (where x =0.0 wt% (D1), 0.2 wt% (D2), 0.4 wt% (D3), 0.6 wt% (D4), and 1.0 wt% (D5)) were prepared with an aqueous solution of zinc acetate dehydrate and tellurium dioxide precursor on a soda-lime glass substrate using the spray pyrolysis technique. XRD study revealed a polycrystalline structure of the films and showed diffraction peaks belonging to paratellurite TeO2 and wurtzite ZnO in all film samples. A peak shift was observed, indicating the presence of ZnO in the TeO2 crystal lattice. FESEM imagery revealed roughness and the film grain size, which decreased when the concentration of ZnO increased. The optical assessment showed superior transparent behavior in the spectrum of visible light and a minor fall in the optical band-gap value when the concentration of ZnO increased. The I-V characteristic obtained for all the thin-film samples showed a linear increase of current as a function of the applied voltages and X-ray doses ranging from 0.0 to 6.0 V and 50–250 cGy, respectively. The I-V characteristic response of the thin-film samples studied were in the order of D3 >D1 >D2 >D4 >D5. The thin films’ dosimetric sensitivity (minimum measurable dose) values were in the range of 0.610–2.180 mAcm2Gy 1 (0.4590–1.6390 mGy) for D1, 0.370–0.940 mAcm2Gy 1 (1.0640–2.7030 mGy) for D2, 0.610–2.280 mAcm2Gy 1 (0.4390–1.6390 mGy) for D3, 0.00200–0.005280 mAcm2Gy 1 (189.3940–357.1430 mGy) for D4, and 0.00040–0.00150 mAcm2Gy 1 (250.0000–666.6670 mGy) for D1. The R2 value (linearity error) of the I-V plots were in the range of 0.879–0.951 (0.0025–0.0057) for D1, 0.966–0.998 (0.0006–0.0025) for D2, 0.869–0.913 (0.0035–0.0065) for D3, 0.860–0.952 (0.000009–0.00005) for D4, and 0.922–0.978 (0.000002–0.000004) for D5. The ZnO-TeO2 thin-film sensor is therefore a candidate material that can be used for miniaturized radiation measuring devices that can be accommodated in smart devices such as smart watches and smart phones