A. B. Magomedov

Realization of a heavily doped and fully compensated semiconductor state in a crystalline semiconductor with a deep impurity band

We use the data on the pressure (up to P=1.5 GPa) and field (up to H=17 kOe) dependence of the Hall coefficient and the resistivity at 77.6 and 300 K in p-CdSnAs2〈Cu〉 to calculate the effective kinetic characteristics of the charge carriers, the density and mobility of the conduction electrons and the holes of the deep acceptor and valence bands, in an interval of excess-acceptor densities Next ranging from 1010–1017 cm−3. We establish that in a heavily doped semiconductor with a deep impurity band at the tail of the density of states of the intrinsic band, with unequal donor and acceptor densities, a a heavily doped and fully compensated semiconductor state is realized under hydrostatic compression. The threshold value of the pressure that initiates the transition into such a state, Pc, depends on the extent to which the impurity band is populated. In p-CdSnAs2〈Cu〉 at Next=NA, where NA is the density of deep acceptors, and T⩽77.6 K the value of Pc amounts to 10−4 GPa. As the population of the deep acceptor band grows, Pc increases and in the limit becomes infinite. We discuss the special features of the electrophysical properties of p-CdSnAs2〈Cu〉 arising from the absence of an energy gap between the states of the conduction band and those of the deep acceptor band.

CdSnAs2 and InAs crystals at hydrostatic pressure up to 9 GPa

The dependencies of resistivity ρ and Hall coefficient R H on hydrostatic pressure up to 9 GPa have been investigated for the two semiconductor materials: CdSnAs2 and InAs. The series of CdSnAs2 samples has n∼ 1016 cm−3 (for those doped with Cu) and n∼ 1018 cm−3 (for undoped) of electron concentration. The InAs undoped sample has n∼ 1016 cm−3. For all CdSnAs2 samples, a polymorphous phase transition takes place at P∼ 4.2 GPa. This transition is accompanied with the decomposition of initial compound. In InAs, the polymorphous phase transition is reversible: after decompression the initial composition is the same. The analysis of ρ (P) in both CdSnAs2 and InAs, points out on the existence of quasi-localized energy levels deep in conduction band.

On the resonant donor level in n-CdTe according to data on electron transport under hydrostatic pressure

Results of quantitative analysis of experimental data on baric (under the hydrostatic pressure to P = 2.5 GPa and T = 300 K) and temperature (in the temperature range of 15–300 K at atmospheric pressure) dependences of the Hall coefficient and electrical conductivity of bulk n-CdTe crystals with the electron concentration of 1015–1017 cm−3 at T = 300 K are presented. The four-level model is used and included deep donor levels arranged in the band gap and in the continuous spectrum of the conduction band and shallow donor and acceptor levels. The location of the donor levels and pressure coefficients of energy gaps between them and the edge of the conduction band are determined.

High pressure as an external factor, effectively governing a chaotic potential of crystalline semiconductors

It has been revealed from pressure, temperature, magnetic and electric fields dependences of kinetic coefficients in doped compensated Ge , p-type InSb, InAs, CdSnAs2 and HgTe, that the observed anomalies of electron transport in the listed above materials are linked to the presence of large-scale fluctuations of ionized impurity concentrations. It is shown, that the influence of chaotic potential begotten by these fluctuations becomes more noticeable when the temperature decreases or the pressure rises.

Investigation of the kinetic characteristics of heavily doped compensated CdSnAs2(Cu)

The concentrational dependences of the Hall coefficient and of the resistivity were used to investigate the interaction of diffusively introduced copper impurity with an ensemble of intrinsic defects inn-CdSnAs2. The initial electron density and the concentrations of theVAs andCuAs defects were found to be of the same order. A study was made of the dependence of the electrophysical properties ofCdSnAs2(Cu) on the population of the impurity band and it was shown that the features of the kinetic characteristics ofCdSnAs2(Cu) are determined by the absence of an energy gap between the bands with a conductivity of opposite sign and by the fact that one of the bands is an impurity band.

Electroresistance of some semiconductors in the phase transition region at high pressure

Abstract In apparata of liquid type piston-cylinder up to 2GPa and toroid with solid anvil up to 25 GPa pressure (P) electrial resistance R(P) in sphere of phase transition (PT) CdSnAs2,SnTeInP,GaAs is investigated, and GaP at T = 300K, and also R(T,P) VTSP YB2Cu306+x in sphere of superconductive transition. In order to describe the substance behaviour in the vicinity of PT, that is, the region of gapped change of R the approximation geterophased structure is used - the effective environment (model GSEE) which checks different configuration of phases inserts and their dependence from P. In order to picture the solid substance behaviour in the vicinity of point PT at high pressure (HP) different methods are used [1–8].

Electronic spectrum and transport phenomena of quasi-gapless semiconductors CdSnAs2 at high pressure

Abstract Hall coefficient R, and conductivity [sgrave] were investigated at T = 2–300K up to H = 15 ke and P = 1.5 GPa. Under pressure influence, transition from disactivational to jump conductivity with a variable step both for electrons of the conductivity band (CB)—that is Anderson transition, and holes of the acceptor resonance band (AB)—that is resonance hybrizational Mott transition (RG MT), occur. In delocalization direction, RG MT was accompanied by increasing of the AB hole mobility of CB electrons. Energy dependence of density of states g(e) had found at 170meV lower of the unperturbated CB edge.

Effect of pressure on the thermo-electromotive force of highly doped and compensated CdSnAs2〈Cu〉 with a deep acceptor level

For a fixed temperature of 300 K on a specimen of CdSnAs2〈Cu〉 acted upon by a uniform pressure of up to 1.5 GPa, the dependence of the thermo-electromotive force on the “narrow” band population is studied for the first time. In agreement with theory, the sign of the thermo-electromotive force is observed to change sign in the studied crystals. The limits of the validity of the “narrow” band approximation are refined.