Self-Compensation Limited Conductivity Of Cl-Doped Cdte Crystals

The conductivity of semi-insulating Cl-doped CdTe crystals produced by Acrorad Co. Ltd. with a resistivity gamma= (3-6) x109 O cm (300 K) was investigated. It is shown that the Fermi level in the band gap is located below the Fermi level in intrinsic CdTe which indicates the hole conductivity of the material. The concentration of holes in the studied crystals is determined to be 2-3 orders of magnitude higher than the concentration of electrons. The statistics of electrons and holes in a semi-insulating semiconductor containing selfcompensation complexes (centers) is considered bear-ing in mind that the effect of background impurities and defects in heavily Cl-doped CdTe crystal is strongly reduced. A method for determining the ionization energy and the compensation degree of deep donors contained in the complexes was applied. It is shown that virtually intrinsic conductivity of the studied CdTe crystals is provided by the donors with ionization energy 0.680.69 eV, whose level is located at 0.05-0.06 eV above the middle of the band gap. Due to strong compensation, the Fermi level turns out below the middle of the band gap. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim