Influence of Impurity Charge Correlation on Free-Carrier Absorption

Abstract

Laboratoire de Physique des Solides (unite associe an CNRS 154)Universite Pierre et Marie Curie 4, pl. Jussieu, 75252 Paris, France Impurity-mediated free-carrier absorption was analyzed theoretically taking into account the possible spatial impurity correlations. The effect of correlations was included via the structure factor S(q) obtained from finite temperature Monte Carlo simulations of ordering in the impurity system. From the comparison of the experimental data with the results of calculations it is demonstrated that the ordering of charged centers exists for HgSe:Fe in a wide temperature range.PACS numbers: 71.45. Gm, 72.30.+q, 75.50.Pp Impurity mediated scattering may be the dominant mechanism of the free--carrier absorption in a wide doping and temperature range. In calculations of the free-carrier absorption it is usually assumed that the impurities are randomly distributed in space. Recently, a detailed description of this absorption, taking into account possible spatial correlation in the distribution of charges on impurities, as well as collective plasma excitations has been formulated ([1-3] and the references therein). The effect of impurity correlations is included via the structure factor S(q), which is equal to unity in totally uncorrelated systems. The ordering in the positions of the charged impurities drastically reduces the probability of carrier scattering related to small momentum transfers. In this momentum region

HgSe Based Mixed Crystals Doped with Fe Resonant Donors

“…The authors employed the fact that the plasmon related free-carrier absorption is sensitive to small momentum transfers. In the paper [45] the experimental results are compared with the finite temperature Monte Carlo simulations. It is shown that the correlation of charged centers exists in a wide temperature range (it is shown that effects due to correlations exist even at room temperature!…”