Synthesis and Development of ZrO2 Film-Based X-ray Sensor for Nondestructive Testing and Medical Imaging Applications

Abstract

The conventional photoconductors commercially used for X-ray sensing are based on Si, a-Se, and CdTeZn. Although several semiconductors such as ZnO, Ga₂O₃, and TiO₂ are explored for X-ray sensing, none meets the commercial standard yet. In this study, the X-ray sensing properties of the ZrO₂ film-based X-ray sensor are explored. The ZrO₂ film of thickness ∼122 μm is synthesized by the sol–gel spin coating method and 1 mm × 1 mm Al is used as connecting electrodes. The ZrO₂ film has a mixture of cubic and tetragonal crystalline phases. The current–voltage (I–V) characteristics of the sensor recorded under dark and X-ray illumination conditions show an ohmic nature. The resistivities under the dark and X-ray illumination conditions are found to be 1.5 × 10⁸ and 2.2 × 10⁷ Ω·cm, respectively. The sensor shows a stable signal-to-noise ratio from 1.5 to 15.0 V bias voltage. The response time of the sensor is <1 s. The sensor is visibly blind between 400 and 700 nm wavelengths. The dose rate characteristics of the sensor are sublinear between 0.015 and 0.248 Gy·s^–1. The X-ray sensitivities at 0.220 Gy·s^–1 for bias voltages of 1.5, 3.0, 4.5, 6.0, and 9.0 V are found to be ∼40.1 ± 0.6, 40.8 ± 1.0, 75.8 ± 0.9, 96.5 ± 1.3, and 149.8 ± 3.2 μC·Gy^1–·cm^–3, respectively. The performance of the device is very promising for developing a commercial standard X-ray sensor.