S. Yu. Paranchich

Low-temperature effects of resonance electronic states at transition-element impurities in the kinetic, magnetic, and acoustic properties of semiconductors

New research results on phenomena due to the existence of electronic resonance energy levels and hybridized states at impurities of transition elements in semiconductors are presented. The data show that the thermal conductivity and ultrasonic parameters of mercury selenide containing iron impurities have resonance anomalies due to the influence of these impurities. A consistent and detailed interpretation is offered for the set of observed effects of hybridized states in mercury selenide with iron impurities. The proposed interpretation of the data obtained on other systems is discussed.

Low-temperature anomalies of the mobility and Shubnikov–de Haas oscillations due to electron resonance scattering on donor impurities in semiconductors. Explanation based on the Friedel approach

Manifestations of electron resonance scattering by donor impurities in the low-temperature conductivity of semiconductors are investigated in the case when the donor resonance energy level of the impurities lies in the conduction band. It is shown that the application of resonance scattering theory in the framework of the Friedel approach can explain the stabilization of the electron density, the maximum of the electron mobility, and the minimum of the Dingle temperature as a function of the concentration of donor impurities and also the anomalous temperature dependence of the mobility due to the resonance. New experimental data are obtained on the concentration, mobility, and Dingle temperature of electrons in mercury selenide crystals containing iron impurities, and it is found that these new results, like those known previously, are in complete agreement with the behavior predicted in the proposed approach. The relation of this approach to the previous interpretation of the concentration maximum of the...

Experimental study of manifestations of resonance scattering of conduction electrons on transition-element impurities in mercury selenide

An interpretation of the experimental data on the low-temperature conductivity and magnetic susceptibility of mercury selenide containing donor impurities of transition elements is developed on the basis of electron resonance scattering theory in the Friedel approach. Both existing data and results obtained in the present study, for solid solutions of chromium, cobalt, and gadolinium, are considered. The results of a fitting of the measured temperature dependence of the electron mobility in HgSe:Cr crystals and concentration dependence of the Curie constant in the impurity magnetic susceptibility of HgSe:Co crystals are analyzed to obtain quantitative confirmation of the idea that resonance donor levels of the impurities chromium and cobalt are present in the conduction band of the respective crystals. The resonance level widths are determined and are found to be an order of magnitude larger than those of iron. It is shown that the observed concentration maximum of the electron mobility in mercury selenid...

Anomalous low-temperature contribution to the heat capacity from hybridized electronic states on transition element impurities

An anomalous nonmonotonic contribution to the temperature dependence of the electron heat capacity of mercury selenide is detected. This is explained in terms of hybridized electronic states on donor impurities. The observed effect is described by a theory of electron heat capacity based on a quantum Fermi-liquid approach including localization and electron-electron interactions. A quantitative interpretation of the experimental dependences yields values for the parameters of the hybridized states that are consistent with those known from other experiments. A new parameter characterizing the electron-electron interaction in the hybridized states is also found.

Anomalies in the temperature dependence of the contribution to the speed of sound from hybridized electronic states of transition element impurities

The temperature dependence of the speed of sound in crystalline mercury selenide with low concentrations of iron impurities is studied. Experiments are conducted in the ranges of concentration and temperature where hybridized electronic states in iron impurities have been observed previously. It is found that at temperatures below 10 K the speed of slow transverse ultrasonic waves has an anomalous nonmonotonic segment of its temperature variation that is related to the influence of the impurities and reflects the existence of hybridized states. The observed anomalies in the sound speed are described in terms of a theory for the electron contribution to the elastic moduli that includes hybridization of impurity states and electron-electron interactions. Fits of the theoretical dependences to the experimental data yield quantitative information on the parameters of the hybridized states and of the Fermi-liquid interaction.

Low-temperature manifestations of hybridized electronic states of iron impurities in the thermoelectric power of mercury selenide

The temperature dependence of the Seebeck coefficient (thermoelectric power) of mercury selenide with iron and cobalt impurities is investigated at low temperatures. In crystals with iron impurities at concentrations close to those corresponding to the concentration maximum of the electron mobility, an anomalously strong decrease of the thermoelectric power is observed in a temperature interval below 25K. This decrease is attributed to a manifestation of resonance scattering of electrons in hybridized states at the iron donor impurities. A fitting of the theoretical temperature dependence to the experimental data permits a quantitative interpretation of the experimental results and yields values of the parameters of the hybridized states which agree with those found from investigations of other effects. In crystals with cobalt impurities no anomalies due to manifestations of hybridized electronic states are observed. This finding is in agreement with the conductivity data and implies a lower value of the ...

Influence of the hybridization of impurity electron states on the quantum magneto-oscillation phenomena in mercury selenide with iron impurities

Experimental study of the concentration dependence of the parameters of the Shubnikov–de Haas and de Haas–van Alphen oscillations in mercury selenide crystals containing iron impurities under conditions where the donor resonance energy level of the impurities falls into the conduction band and hybridization of the electronic states occurs. The observed concentration dependence of the Dingle temperature and g factor of the electrons exhibit minima correlated in position with the maximum of the electronic mobility. It is shown that the observed anomalies can be explained on the basis of a previously developed theory of hybridization effects.

Resonant effects in the manifestation of hybridized electronic states of iron impurities in the temperature dependences of the absorption coefficient and velocity of ultrasound propagation in mercury selenide

The temperature dependences of the absorption coefficient and phase velocity of 52-MHz ultrasonic waves in iron-doped mercury selenide crystals are studied. The presence of impurities in concentrations of about 1019 cm−3 is found to initiate the appearance of a resonance peak in the absorption coefficient at a temperature of about 5 K and the corresponding anomaly in the velocity of the slow transverse wave propagating in the 〈110〉 direction. It is shown that the observed effects can be accounted for by the interaction of ultrasound with electrons in the states created in hybridization of the iron impurity donor states with the conduction band states of the crystal. A straightforward theoretical description and quantitative interpretation of these effects are proposed and used to derive data on the hybridized states, which conform with the earlier treatment of the temperature and concentration anomalies of conductivity in the crystals under study.

Shubnikov-de Haas oscillations in HgSe〈Fe〉 and HgSe〈Co〉 under hydrostatic pressure

Shubnikov-de Haas oscillations have been studied in the gapless semiconductors HgSe〈Fe〉 and HgSe〈Co〉 under hydrostatic pressure. It is shown that in HgSe〈Fe〉 an increase in pressure results in a decrease in the electron density, which fits within the framework of the Kane model with constant Fermi energy. In contrast, in HgSe〈Co〉 the electron density is independent of the pressure, i.e., Fermi-level pinning is absent.

Effect of Fe, Co, and Cr impurities on the thermoelectric properties of Cd x Hg1−x Se

We have studied the effect of doping with 3d transition metals (iron, cobalt, and chromium) on the thermoelectric properties of single crystals of CdxHg1−xSe solid solutions at temperatures from 77 to 400 K and the effect of thermal annealing in Hg or Se vapor on their electrical properties. The results indicate that chromium and cobalt produce no energy levels in the band structure of CdxHg1−xSe solid solutions. Therefore, these dopants do not create resonant donor levels superimposed on continuum states of mercuric selenide. Fe doping produces an energy level whose position can be controlled by varying the composition of the solid solutions.