Some Studies on Electrical Behaviour of Red Mercuric Iodide Single Crystals

Red mercuric iodide (alpha-HgI2) has attracted considerable interest in the last over three decades or so due to its applicability in room temperature detection of X-rays and gamma-rays. The single crystal plates of alpha-HgI2 are used as solid-state ionization chambers for the detection of X-rays and low energy gamma-rays and as photodetectors in conjunction with several scintillating materials in the scintillator-based gamma ray spectrometers. In these applications, a single crystal plate of alpha-HgI2 is sandwiched in between two parallel electrodes to produce a device. Several techniques have been used in the past to study electrical, optoelectronic and radiation detection properties of such devices. However, no attempt is made in the past to understand the behaviour of such a device under alternating electric fields. Also, no attempt is made in the past to understand the effect of frequency and temperature on the dielectric properties of this material. In the present paper, we are reporting the results of our investigations on electrical behaviour of some alpha-HgI2 single crystals obtained using complex impedance spectroscopy. The frequency and temperature dependences of the electrical properties of the alpha-HgI2 single crystals have also been obtained for the first time. These results will be presented and discussed for a better understanding of the electrical behaviour of radiation detectors made of this material.