## 3 Results and Discussion
Also, from the graphs, we can notice that the 1 mm ZnO-Pb disk responded to radiation more than the thin film because of the presence of Pb, which has a high \(Z_{\text{eff}}\) under low radiation dose, which interacts with radiation through the photoelectric effect and produces more photons, leading to increase in the current [26]. The current and voltage sensitivity values of TF and 1 mm ZnO-Pb were calculated by plotting (I-Dose value) and (V-Dose value) curves, as mentioned in Figure 5. The voltage of the system was found to be decreased by increasing the absorbed dose from 3.13 V to 2.90 V, within standard error \(\pm\)0.0118 V for the thin film and from 3.57 V to 3.06 V \(\pm\) 0.03 V for the 1 mm disk type. The linearity of the sensors was shown to be 94.5% for the thin film and 96.5% for the 1 mm ZnO-Pb. In addition, small thicknesses are more sensitive to low radiation doses  
Figure 4: (**A**) Linear and saturation regime for the thin film and (**B**) linear and saturation regime for the 1 mm disk ZnO-Pb, under low absorbed dose. than high radiation dose [27]. The threshold voltage of the ZnO-Pb samples was calculated by using Equation (1); it shows that for all samples, the threshold voltage rose by increasing the absorbed dose value and increasing the thickness of the samples (Figure 6). According to the graphs, increase in the thickness of ZnO-Pb from several \(\upmu\)m to 1 mm leads to a noticeable magnification in the \(\Delta\)V\({}_{\text{TH}}\) from 0.06 to 0.1 V for the thin film, and from 0.21 to 0.45 V for the 1 mm disk. Furthermore, as the sample thickness rises, so does the sensitivity of the dosimeter from 1.42 mV/mGy for the thin film to 6.42 mV/mGy for the 1 mm disk under radiation dose 70 mGy. Because the thick gate allows for more effective separation of electron-hole pairs produced within the oxide, the sensitivity will improve [28]. The sensitivity of the samples was measured using Equation (6); the sensitivity of the samples decreased on increasing the dose and increased with a rise in thickness of the devices. The characteristic results of the ZnO-Pb thin film and disk type are tabulated in Table 2. One feature of the EGFET sensor that is observed with every detector is the inherent reduction in sensitivity with increased absorbed dose. This is thought to be produced by changes in the effective electric field supplied to the EGFET during irradiation, which results in a buildup of holes at the gate oxide contact [29]. Figure 5: (**A**) Voltage vs. dose and (**B**) current vs. dose for both the thin film and the disk ZnO-Pb. Figure 6: (**A**) Threshold voltage vs. dose and (**B**) sensitivity vs. dose for the ZnO-Pb thin film and disks irradiated with the low dose. Current-voltage curves were plotted as shown in Figure 7A,B. The figures describe the radiation sensing characteristics of the ZnO-Pb thin film and the 1 mm disk type under high absorbed doses (1, 5, and 10 Gy). These curves reflect a higher current value, compared to the same previous dosimeters exposed to low radiation doses. Moreover, the current value increased more in the sample 1 mm ZnO-Pb disk type than in the thin film. This is because ionizing radiation produces structural flaws (called color centers), which cause their density to vary as X-ray exposure increases [30]. High-energy radiations alter the physical characteristics of the materials through which they pass. The existence of oxygen vacancies influences the reactivity of oxide materials [31]. Moreover, the current value increased more in the sample 1 mm ZnO-Pb disk type than that in the thin film--\(\Delta\)I for the thin film = 73 \(\mu\)A and 1 mm = 189 \(\mu\)A. Oxygen vacancies are present naturally in all oxides as Shottky or Frenkel faults, and their density can be raised or decreased in a variety of methods [32]. In the former scenario, the vacancy relates to two electrons. Increasing the radiation dose leads to rise in the defects.