Determination of carrier effective mass, impurity energy levels, and compensation ratio in Ga4Se3S layered crystals by Hall effect measurements

In this work, the dark electrical resistivity, charge carriers density and Hall mobility of Ga4Se3S single crystals have been measured and analyzed in the temperature region of 200-350 K. The data analyses have shown that this crystal exhibits an extrinsic n-type of conduction. The temperature-dependent dark electrical resistivity analysis reflected the existence of energy level as 0.31 eV. The temperature dependence of carrier density was analyzed by using the single donor-single acceptor model. The latter analysis allowed the determination of electron effective mass as 0.38m(0), hole effective mass as 0.42m(0), donor impurity energy level as 0.45 eV, acceptor-donor concentration ratio (N-a/N-d) as 0.97 and a donor-acceptor concentration difference as N-d - N-a = 1.5 x 10(11) cm(-3). The Hall mobility of Ga4Se3S is found to increase with decreasing temperature following a power law of slope of similar to(-6.3). The abnormal behavior of mobility was attributed to the domination of phonon scattering and/or crystals anisotropy. (c) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.