Bismuth iodide crystals as a detector material: some optical and electrical properties

Abstract

This paper describes the preliminary results obtained from our study of optical and electrical properties of BiT3 crystals. The bismuth iodine polycrystals were grown using commercial starting material by vertical Bridgman method. For our measurements we used only single crystal samples that were cut out from grown crystals perpendicular to C6-axis. BiT3 is a layered hexagonal lattice similar to the Pb12 lattice, where two-thirds of the metal sublattice sites are occupied and the remaining one-third are vacant. The average atomic number of the bismuth iodide ((Z) = 60.5) is very close to that of lead iodide ((Z) = 62.7). Therefore, Bi13 is similar to the better known Pb12 and can be a promising detector material. Our measurements have shown that bismuth iodide crystals have resistivity on the order of 1 Gcm and energy gap Eg 1.72eV. The photocurrent, as a function of bias and wavelength, as well as detector responses from excitation by blue LED and X-ray tube photons were measured. The value of the mobility-lifetime product of the electron (rc l05cm2/V) was estimated by the Hecht technique. The optical characterization also included measuring of quantum efficiency for BiT3 detector. The experimental results demonstrate the potential feasibility of using BiT3 as detector material operating at room temperatures.

Growth, fabrication, and testing of bismuth tri-iodide semiconductor radiation detectors

“…Resistivity values in the range of 10 12 e10 13 U-cm were measured for BiI 3 platelets grown by the physical vapor deposition (PVD) (Fornaro et al, 2004b), , and (Aguiar et al, 2009). Resistivity values in the range of 10 10 U-cm were reported for BiI 3 platelets grown by PVD as well as for single crystals grown by the Bridgman method (Dmitriev et al, 1999), (Matsumoto et al, 2002), and (Nason and Keller, 1995). Growth of BiI 3 from zone refined powder has also been reported with a resistivity in the range of 10 6 U-cm (Kim et al, 2013).…”

“…There are however some material and growth issues with both HgI 2 and PbI 2 (Lintereur et al, 2008) and as a result these materials have not gained much popularity. BiI 3 is a semiconductor material, which has properties similar to HgI 2 and PbI 2 , but it does not share their major limitations (Dmitriev et al, 1999). BiI 3 has high effective atomic number (since Z Bi ¼ 83 and Z I ¼ 53) and high density (5.78 g/cm 3 ) and thus has a very good photon stopping power (Matsumoto et al, 2002).…”

Bismuth Tri-Iodide Polycrystalline Films for Digital X-Ray Radiography Applications

“…Attempts have been made at growing bismuth tri-iodide single crystal platelets by open flow sublimation and recrystallization [35], and bulk monocrystals by PVD [26] and also by the vertical Bridgman method [25], [27], [36]. Only one reference was found to the growth of bismuth tri-iodide films, but those were grown onto a monocrystalline substrate (lead iodide) and had thicknesses between 0.01 and 0.1 m [37].…”

“…Bismuth tri-iodide, like mercuric and lead iodide, is a layered compound whose crystal lattices are built from three layer packages (I-Hg-I; I-Pb-I; I-Bi-I) with weak van der Waals bonding between adjacent planes of iodine atoms and perpendicular to the c axis [25]- [27]. This weak bonding determines that the three materials are soft, and have to be handled carefully.…”

Investigation of Bismuth Triiodide (BiI3) for Photovoltaic Applications

“…4,10 The hole mobility is expected to be much lower due to the difference in carrier effective masses; previously we calculated the hole and electron effective masses in the BiI 3 R3 phase to be 10.39 and 1.85, respectively. 3 Electron mobility-lifetime products of 1.4×10 -6 cm 2 /V and 9.5×10 -6 cm 2 /V have been reported, 5,11 corresponding to electron diffusion lengths of 1.9 μm or 4.9 μm, respectively. These diffusion lengths are on the order of the thickness of typical thin-film solar 4 cells, suggesting that the electronic properties of BiI 3 may enable PV performance.…”