CHARGE-CARRIER TRANSPORT IN ALPHA-HGI2 SINGLE-CRYSTALS

Photoconductivity in red mercuric iodide single crystals grown by poly mer controlled growth (PCG) technique have been studied in the wavelen gth range 450-700 nm at different temperatures ranging from 80 to 300 K. Various aspects of charge carrier optical generation in these cryst als have been discussed in detail. Analysis of room temperature photoc onductivity spectra helped in determining the mobilities (mu(o) mu(h)) , effective lifetimes (tau(o) tau(h)) and surface recombination veloci ties (s(o) s(h)) of the charge carriers in these crystals. The values of mobilities (mu(e) = 101 cm(2)/V s, mu(h) = 10 cm(2)/V s), effective lifetimes (tau(e) = 4 mu s, tau(h) = 0.68 mu s) and hole surface reco mbination velocity (S-h = 3.6 x 10(4) cm/s) match quite well with thos e reported in the literature for nuclear radiation detector grade alph a-HgI2 single crystals. A high electron surface recombination velocity (s(e) = 2.1 x 10(5) cm/s) indicates that the surface conditions of th e as-grown PCG crystals are not optimal regarding the electron surface recombination.