Trapping effects in silver-doped mercuric iodide crystals

Abstract

Electrical and photoelectrical characteristics of silver-doped mercuric iodide crystals were investigated with a view to study the trapping phenomena in these crystals. Trapping parameters were determined by thermally-stimulated-current measurements, photoluminescence spectra, spectral response, and photoconductive decay measurements. The effects of temperature on pulse height under uniform illumination was measured in the temperature range of −100 to +100 °C. Resistivity changes and I-V characteristics are also discussed. Results of the experiments indicate a strong possibility for the existence of at least two main impurity levels in silver-doped HgI2—one, a hole trapping acceptor level at 0.73 eV above the valence band, and another, possibly a donor level, at 0.26 eV below the conduction band. The effect of a compensated acceptor level on polarization is also shown.