Crystal Growth of α-HgI₂ by the Temperature Difference Method for High Sensitivity X-ray Detection

Abstract

α-HgI 2 is a promising material for room temperature X-ray detection. A facile temperature difference method is designed to grow 4 × 4 × 2 mm 3 α-HgI 2 bulk crystal from KI aqueous solution. Characterization results indicate the as-grown high quality crystals are single-crystalline and possess a standard bandgap (E g = 2.16 eV at 300 K) and high electrical resistivity (10 10 Ω·cm). Utilizing the as-grown crystal, moreover, a photoconductive type prototype X-ray detector is fabricated. The detector behaves at high X-ray sensitivity, which is improved by one order of magnitude in comparison with previous results from solution grown α-HgI 2 . In addition to α-HgI 2 , the crystal growth of other halides materials which are used for X-ray detection, e.g., PbI 2 , HgBr 2 , BiI 3 , may also benefit from the presented temperature difference method.

Optimization of the HgI2 Crystal Preparation for Application as a Radiation Semiconductor Detector

“…The determined resistivity values from each crystal encapsulated are summarized in Table 4. The best resistivity result (3.9 x 1010 Ωcm) was obtained for the detector encapsulated with resin #3 (50% -100% of methyl-acetate and 5% -10% of n-butyl-acetate), which value is close to those described by Zhang et al (2015). It was not possible to evaluate the crystal encapsulated with resin # 1 due to the chemical reaction occurrence between the resin and the HgI 2 crystal surface with the electric contacts (Figure 12a), not allowing its use as a radiation detector.…”

Aqueous Solution Growth of Millimeter-Sized Nongreen-Luminescent Wide Bandgap Cs4PbBr6 Bulk Crystal

“…This means that Cs 4 PbBr 6 may have intrinsic high electrical resistivity, which will be beneficial for achieving low dark current for application in photon detection. 12,31 The electronic band structure and density of states (DOS) of Cs 4 PbBr 6 are calculated using density functional theory (DFT), and the results are shown in Figure 3. As seen from Figure 3a, the conduction band (CB) bottom is at Γ point in the Brillouin zone.…”

“…12 Additionally, considering that Cs 4 PbBr 6 is composed of heavy elements (Z Cs = 55, Z Pb = 82, Z Br = 35), bulk Cs 4 PbBr 6 crystal may also have possible excellent performance in radiation detection such as X-ray detection. 31 And studies in these two aspects will be our pursuit in the future.…”

“…Thus, it can be speculated that Cs 4 PbBr 6 will possibly be intrinsic or weak p-type semiconductor. This means that Cs 4 PbBr 6 may have intrinsic high electrical resistivity, which will be beneficial for achieving low dark current for application in photon detection. , …”

2D van der Waals Molecular Crystal β‐HgI2: Economical, Rapid, and Substrate‐Free Liquid‐Phase Synthesis and Strong In‐Plane Optical Anisotropy

“…[ 6 ] As a member of van der Waals iodide, HgI 2 also has a potential to be prepared as a new 2D material. Till now, there have been some reports on the growth method and structural characteristics of bulk HgI 2 , [ 7 ] which is a main candidate for room temperature X‐ray detection [ 7,8 ] with a bandgap of 2.13 eV, a high resistivity of 10 13 Ω cm, and high atomic number. Because of the advantages like high photoelectric absorption coefficient, good stopping power for X and γ rays, high detection efficiency, excellent energy resolution, and an ability to work and be stored at room temperature, it can be used to make portable spectrometer with small size and lightweight, such as counters, spectrometers, photoelectric detector, position sensitive detector, etc.…”