Abstract
The relationship between depositing temperature and crystallinity of grain for HgI2 polycrystalline film with 170 cm2 in area deposited by Physical Vapor Deposition (PVD) was investigated, considering the matches with readout matrix pixelation for female breast examination. The different depositing temperatures, 35, 40 and 45 °C, were carried out with the same source temperature, 100 °C, corresponding to 2–2.5 h of the growth period. The films deposited were investigated by XRD, SEM, and I–V. The results show that the grain size of the films grown increases with the depositing temperature from 35 to 45 °C. At 45 °C, the polycrystalline film has a preferred microcrystal orientation with 97.2% of [001]/[hkl] and grain size is about 180–220 μm. A 256 × 256 pixels X-ray image of a bolt, key, and wiring displacement was present distinctly with 50 keV with 6 mA current of X-ray generator. Our discussions on the relationship between depositing temperature and crystallinity of grain of film suggest that the higher growth temperature, the better crystallinity and excellent preferred microcrystal orientation of grain, however, with complementary bigger grain size. For matching readout matrix pixelation, the growth period of poly-films would be reduced appropriately for reasonable grain size and preventing the crack of films deposited.
Highlights
Among a variety of detector materials, such as CdTe [1,2], PbI2 [3,4,5], BiI3 [6,7], and HgI2 [8,9,10,11,12], HgI2 turned out to be the superb one for direct and digital X-ray imaging for the last 15 years
We investigated the correlation between depositing temperature and morphology of grains of polycrystalline HgI2 with the area of 13 × 13 cm2 in area and >500 μm in thickness by Physical Vapor Deposition (PVD)
Xu [27] optimized the growth temperature of HgI2 single crystal and polycrystal films, as shown in Equation (1), and thought that the depositing temperature would increase with the increase of source temperature in a seal system
Summary
Among a variety of detector materials, such as CdTe [1,2], PbI2 [3,4,5], BiI3 [6,7], and HgI2 [8,9,10,11,12], HgI2 turned out to be the superb one for direct and digital X-ray imaging for the last 15 years. There is still a surge of interest in large area mercuric iodide (HgI2) polycrystalline films in the application of digital radiographic detectors for medical diagnostic, scientific, and industrial applications on room-temperature X-rays [11,13,14,15], especially the application of female breast lesion. Compared with PbI2, HgI2 imagers demonstrate much sharper images due to excellent spatial resolution [9], which is easier to clearly detect the nidus of female breast cancer. As a layered structure material, the band gap of HgI2 is about 2.13 eV, which matches the low-energy X-ray [13]. Some methods have been used for the growth of HgI2 poly-film, such as vapor phase deposition, laser ablation, screenprint [18,19], casting technique [20], electrode deposition, and growth from solution [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
