Purification and Improved Nuclear Radiation Detection of Tl₆SI₄ Semiconductor

Abstract

The wide-band-gap semiconductor Tl6SI4 (2.14 eV) has high photon stopping power and is a promising material for detecting X-rays. In order to improve its photoresponse to low-flux γ-rays, material purification prior to crystal growth is crucial. In this contribution, we report effective purification protocols, impurity analysis, followed by synthesis and crystal growth, charge transport, and detector performance of large-sized Tl6SI4 crystals. Purification methods of evaporation and zone refining were developed, and their high effectiveness was confirmed by impurity analysis via glow discharge mass spectrometry. Centimeter-sized single crystals were grown using the Bridgman method. The improved properties after material purification were confirmed by photoluminescence measurements. The energy of the valence band maximum of a Tl6SI4, measured with photoemission spectroscopy in air (PESA), is ∼5.34 ± 0.05 eV. Detector devices fabricated from the single crystal exhibit a high resistivity of 5 × 1012 Ω·cm. The detector shows promising photoresponse under 22.4 keV Ag Kα X-rays and 122 keV γ-rays from 57Co. Spectroscopic energy resolution was achieved for 5.5 MeV α-particles from a 241Am radiation source with a full width at half-maximum of 27% at an electric field intensity of 2500 V·cm–1. On the basis of its spectral response to 57Co γ-rays, the electron mobility-lifetime product μeτe was estimated as 1.4 × 10–5 cm2·V–1. Drift mobility measurements via a time-of-flight technique using spectral photoresponse induced by α-particles reveal a high electron mobility of 35 ± 7 cm2·V–1·s–1.

Purification and Improved Photoelectric Properties of Lead-Free Perovskite Cs3Bi2Br9 Crystals

“…Subsequently, high-quality Hg 2 Br 2 crystals with little lattice distortions were obtained using purified raw materials. Lin et al [16] used the PVT method to remove most of the impurities in TlI 4 raw materials, as evidenced by GDMS analysis, resulting in the growth of high-performance Tl 6 SI 4 crystals with a high resistivity of 5 ×1 0 12 Ω•cm and a high electron mobility of 35 ± 7 cm 2 •V −1 •s −1 , achieving spectroscopic detection with an energy resolution of 27% for 241 Am α-particles. It can be seen that removing impurities from raw materials using the PVT method can remarkably improve the photoelectric properties of semiconducting crystals.…”

Combined Purification and Crystal Growth of CsPbBr3 by Modified Zone Refining

“…[6][7][8] However, the commercial benchmark material, CZT, still suffers from a high concentration of Te inclusions/precipitates, uneven distribution of Cd and Te, and high production cost. [7,[9][10][11] TlBr detectors suffer from chemical instability and low hardness. [5,12,13] Therefore, it is important to explore alternative high-performance radiation detection materials suitable for low-cost, high-volume production.…”

High Yield Solution Growth of FACsPbBr3 Single Crystals with Low Defect Density for Gamma-ray Spectroscopy

“…Therefore, the solution method does not need extra energy-consuming purification processes for the precursor materials like the melting methods 36 . In addition, the as-grown crystals are very transparent, and do not need another zonerefining process 37 . All of these contribute to a dramatically manufacturing cost decrease.…”