Dose-dependent x-ray sensing nature of nanocrystalline bismuth phosphate thick films

Abstract

Bismuth and its compounds have been used in various optoelectronic devices because of their unique physical properties and non-toxic nature. In this present study, nanocrystalline bismuth phosphate (BiPO4) was synthesized by solid-state double exchange reaction and then processed at 150 °C for 30 min under nitrogen gas flow. The phase, morphology, purity and band gap of the sample were analyzed respectively using x-ray diffraction, scanning electron microscopy-energy dispersive x-ray, Fourier transform infrared, Raman and diffuse reflectance spectroscopy. The obtained results reveal that the sample exists in hexagonal phase with crystallites in sub-spherical morphology (∼84 nm) and having a direct transition band gap of 4.52 eV. Furthermore, the x-ray attenuating nature of nanocrystalline BiPO4 thick film was examined using an intra-oral diagnostic x-ray machine interfaced with a Suniray-2 radiography image sensor. A theoretical validation of the obtained x-ray attenuating nature was carried out using the NIST-XCOM online resource. Then, x-ray-induced photocurrent was measured for nanocrystalline BiPO4 thick (200 µm) film for four different doses (mGy) exposed under biased condition (2 V). A grain boundary double Schottky potential barrier height (ϕb) model was applied to explain the observed linear dose-dependent x-ray sensing nature.