The effects of vacancy induced acceptors in zero gap semiconductors, like in HgTe, are treated by the resonant state theory. First, one scattering center is considered, then multiple scattering is developed in the case of acceptor concentrations up to 1 × 1022 m−3. In this investigation the effects of even higher acceptor concentrations (N ≥ 1 × 1023 m−3) are elucidated. It is shown that in this case the resonant state model is no longer applicable since the randomly distributed impurities result in a fluctuating potential field. Thus the impurity disorder introduces an Anderson type conduction process. This is characterized by a large change in the mobility when the Fermi level goes through the acceptor band. These mobilities, related to the Anderson type conduction mechanisms, are in good agreement with the experimentally determined ones in the case of HgTe. While using the resonant state theory, the predicted mobilities are not in satisfactory agreement with the measured ones in the high acceptor concentration range analyzed in this investigation.
Hgl-,Cd,Te, with z = 0.15 is a semimetal a t low temperature (4.2 K) and becomes a narrow-gap semiconductor a t higher ones (77 K). Its transport properties are measured a t different temperatures, magnetic fields, and hydrostatic pressures. Based on the measured data, an analytical three-band model is developed to calculate the concentrations and mobilities of the resulting two types of electrons and one type of holes. The existence of the slow electrons are related to the presence of acceptor states in the conduction band, as it is already elucidated in the case of zerogap HgTe. The concordance of the calculated transport properties, based on this model, with the measured ones supports the subsistence of three types of carriers in the narrow-gap HgCdTe.Hgl-,Cd,Te mit z = 0,15 ist ein Halbmetall bei tiefen Temperaturen (4,2 K) und wird ein schmalluckiger Halbleiter bei hoheren Temperaturen (77 K). Seine Transporteigenschaften werden bei verschiedenen Temperaturen, Magnetfeldern und hydrostatischen Drucken gemessen. Auf Grund der gemessenen Daten wird ein analytisches Dreibandmodell entwickelt, um die Konzentrationen und Beweglichkeiteu der resultierenden beiden Elektronensorten und der einen Locherart zu berechnen. Die Existenz der langsamen Elektronen wird auf Akzeptorzustande im Leitungsband zuruckgefuhrt, wie bereits fur den Fall des Null-Gap-HgTe gefunden wurde. Die Ubereinstimmung der nach diesem Model1 berechneten Transporteigenschaften mit den gemessenen bestiitigt die Koexistenz von drei Tragerarten in schmalluckigem HgCdTe.
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