Development of Ag-Doped ZnO Thin Films and Thermoluminescence (TLD) Characteristics for Radiation Technology

Abstract

This work examined the thermoluminescence dosimetry characteristics of Ag-doped ZnO thin films. The hydrothermal method was employed to synthesize Ag-doped ZnO thin films with variant molarity of Ag (0, 0.5, 1.0, 3.0, and 5.0 mol%). The structure, morphology, and optical characteristics were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), photoluminescence (PL), and UV-vis spectrophotometers. The thermoluminescence characteristics were examined by exposing the samples to X-ray radiation. It was obtained that the highest TL intensity for Ag-doped ZnO thin films appeared to correspond to 0.5 mol% of Ag, when the films were exposed to X-ray radiation. The results further showed that the glow curve has a single peak at 240-325 °C, with its maximum at 270 °C, which corresponded to the heating rate of 5 °C/s. The results of the annealing procedures showed the best TL response was found at 400 °C and 30 min. The dose-response revealed a good linear up to 4 Gy. The proposed sensitivity was 1.8 times higher than the TLD 100 chips. The thermal fading was recorded at 8% for 1 Gy and 20% for 4 Gy in the first hour. After 45 days of irradiation, the signal loss was recorded at 32% and 40% for the cases of 1 Gy and 4 Gy, respectively. The obtained optical fading results confirmed that all samples' stored signals were affected by the exposure to sunlight, which decreased up to 70% after 6 h. This new dosimeter exhibits good properties for radiation measurement, given its overgrowth (in terms of the glow curve) within 30 s (similar to the TLD 100 case), simple annealing procedure, and high sensitivity (two times that of the TLD 100).

Keywords: Ag; ZnO; dosimetry; fading; linear response doses; sensitivity; thermoluminescence.

Figure 1

The schematic diagram of the experimental set-up for X-ray irradiation dose using Toshiba KXO-50S X-ray.

Figure 2

The X-ray diffraction pattern of undoped ZnO and Ag-doped ZnO thin films.

Figure 3

FE-SEM images of the (a) pure ZnO and silver dopant at (b) 0.5%; (c) 1%; and (d) 3%, respectively.

Figure 3

FE-SEM images of the (a) pure ZnO and silver dopant at (b) 0.5%; (c) 1%; and (d) 3%, respectively.

Figure 4

The EDX spectrum for undoped and Ag-doped ZnO thin films with typical mapping images.

Figure 5

(a) Room temperature PL spectra of pure ZnO and Ag-doped ZnO 1%, 0.5% mol thin films, and (b) Gaussian deconvolution of Ag-doped ZnO thin film.

Figure 6

Optical transmittance for undoped ZnO and Ag-doped ZnO thin films.

Figure 7

The bandgap for undoped ZnO and Ag-doped ZnO thin films.

Figure 8

The glow curves of Ag-doped ZnO thin films with different concentrations of Ag percentage.

Figure 9

Glow curve of Ag-doped ZnO thin films as a function of heating rate.

Figure 10

TL response of Ag-doped ZnO thin films as a function of heating rate.

Figure 11

The TL response of Ag-doped ZnO thin films with different annealing temperatures.

Figure 12

The TL response of Ag-doped ZnO thin films with different annealing times.

Figure 13

The linearity of response dose irradiated with X-ray (0.1–4) Gy.

Figure 14

Reproducibility of Ag-doped ZnO thin films irradiated 4 Gy with X-ray.

Figure 15

Thermal fading characteristics of Ag-doped ZnO thin films exposed to X-ray.

Figure 16

The optical fading of Ag-doped ZnO thin films exposed to sunlight and fluorescent light.

Figure 17

Percentage depth dose curve of the Perspex phantoms in 30 cm × 30 cm field size at 60 kVp of the X-ray energy with delivery dose 3 Gy.