Study of trapping levels in α-HgI2 crystals by UV and isothermal current measurements

UV spectra and isothermal current (I–t curves) measurements have been performed in order to determine the trapping levels in α-HgI2 crystal grown by a static sublimation method. Four absorption bands, with different absorption intensity, were found at 1572.5, 1729.2, 2117.5 and 2305.8 nm in the UV spectra. According to a simple energy level model, the first two, corresponding to 0.79 0.01 and 0.72 eV, respectively, were confirmed to be the absorption of trapping levels from the I–t data, whereas the last two were not assigned due to insufficient data from the I–t measurements. Our discussions on the characterization of the energy levels suggest that the four absorption bands in the UV spectra may be derived from structural defects in the HgI2 crystal.