Mercuric iodide is an interesting material for room temperature X-ray or gamma-ray spectrometers. This is due to its wide band gap (2.13 eV) and its high atomic numbers (80/53). A spectral resolution of better than 4% at 137 Cs has been reported. Mercuric iodide detectors suffer from polarization i.e., their electrical properties change with time and it will affect and reduce initial high spectral resolution and other electrical properties. This research paper is studying the polarization phenomena using capacitance measurements with low bias voltages and assuming a metal insulator semiconductor (MIS) structure.