Measurement of the drift velocity of charge carriers in mercuric iodide

Abstract

The time-of-flight technique has been used to determine the electron and hole drift velocities in mercuric iodide crystals. The electron mobility is constant up to fields of 30 kV/cm, equal to 100 cm2/V sec at room temperature, and proportional to T−0.9 in the temperature range 114–300 °K. The hole mobility is equal to 4 cm2/V sec at room temperature and exhibits a T−1.7 dependence between 140 and 240 °K and a T−3.7 dependence between 240 and 350 °K.

Vapor Growth of Mercuric Iodide Tetragonal Prismatic Crystals

“…HgI 2 is considered a candidate for room-temperature γ-ray detector material, mainly due to its high atomic numbers (Z Hg = 80, Z I = 53) and wide band gap (E g ∼2.13 eV at 300K). As in Figure 1.1, because of its high Z constituents, HgI 2 has the highest photoelectric absorption coefficient compared to that of Si, Ge, or CdZnTe, while it is comparable to those of PbI 2 and TlBr, for γ-ray 1 energies in the range of 80 and 1000 keV. Mass absorption coefficients of γ-ray detector materials.…”

“…Despite these favorable attributes, HgI 2 suffers from several drawbacks, such as low hole mobility [2][3][4], low yield strength [5][6][7], and polarization [8][9][10][11][12]. These drawbacks, unfortunately, have prevented a wider use of HgI 2 single crystals as room temperature γ-ray detectors.…”

“…direction are held together by van der Waals forces. 2 According to [37], the formation of HgI , except the highlights, were created using DRAWxtl [58]. (c) The tetrahedral layers are held together by van der Waals forces.…”

Textured α-HgI2 ceramics for sensitive X-ray detection

“…The photo-generated holes are thus collected by this electrode, while the electrons are collected by the rear electrode. However, in HgI 2 electrons are much more mobile than holes [26]. In addition, owing to the limited X-ray penetration depth, most carriers are generated closer to the front electrodes, so that electrons have the longest pathway to their collecting electrode.…”

“…In the case of a material such as α-HgI 2 with anisotropic transport properties, the control of the crystal grain orientation is thus crucial. α-HgI 2 has a tetragonal unit cell [25] and a structure made of layers of HgI 4 tetrahedra oriented perpendicular to the c axis, with the highest electron mobility along this axis [26][27]. Therefore obtaining polycrystalline α-HgI 2 with the c axis of the grains oriented along the charge collection direction is a key requirement to achieve optimal transport properties.…”