M. K. Sharov

Microhardness and density of PbTe1−xHalx (Hal = Cl, Br, I) solid solutions

Microhardness data for PbTe1−xHalx (Hal = Cl, Br, I) solid solutions are used to evaluate the halogen solubility in PbTe. The density of the PbTe1−xHalx solid solutions is shown to drop with increasing halogen content, with a rate decreasing in the order Cl > Br > I. The density data are interpreted in terms of self-compensation.

Transport Properties of Ga-Doped PbTe Thin Films on Si Substrates

Thin PbTe films on Si substrates were doped with Ga via annealing in the vapor produced by heating a Ga(l) + GaTe(s) mixture (GaTe(s) + L1+ Vequilibrium). Electrical measurements showed that the vapor-phase doping reduced the hole concentration in the films by more than two orders of magnitude. IR irradiation was found to reduce the resistivity of the PbTe films by a factor of 40–100. The films annealed in the vapor over GaTe(s) + L1for the longest time exhibited an anomalous temperature variation of resistance, which was interpreted as due to the limited Ga solubility in PbTe.

Lattice parameter of PbTe1−x Cl x solid solutions

The lattice parameter of PbTe1−xClx solid solutions is shown to be a nonmonotonic function of chlorine content, with a minimum at x = 0.005. The results are interpreted in terms of a self-compensation model.

Silver solubility in PbTe crystals

Silver solubility in lead telluride single crystals has been determined using electron microscopy, x-ray microanalysis, microhardness tests, and hydrostatic density measurements. The results indicate that the limit of the Pb1 − xAgxTe solid-solution series is near x = 0.006. With increasing silver content, the density of the Pb1 − xAgxTe solid solutions drops, while their microhardness rises.

Pb and In Codeposition in the Vacuum Growth of PbTe Films on Si Substrates

Pb1 – xInx melts were proposed to be used as In vapor sources, in combination with separate Pb and Te sources, in depositing PbTe<In> films onto Si substrates by a modified hot-wall method. Under the assumption that the presence of Pb in Pb1 – xInx melts may raise the In partial pressure, the vaporization behavior of Pb1 – xInx (0.05 ≤ x ≤ 0.70) was studied between 900 and 1200 K in the reaction chamber of the deposition unit. Using electron probe x-ray microanalysis and x-ray diffraction, all the deposited films were shown to contain In. The In content of the Pb1 – yIny deposits varied in the range 0.002 <y < 0.07 and increased with increasing In concentration in the Pb1 – xInx melt and with increasing vapor source temperature. The vapor over molten Pb1 – xInx was shown to exhibit a positive deviation from ideality.

Plasma resonance in IR spectra of reflection of solid solutions PbTe 1−xBrx (c)

The concentration of free electrons, Fermi level, and specific electric conductivity on the basis of the studied coefficient of IR reflection in the region of plasma resonance of solid solutions PbTe1 − xBrx is determined. It is found that the concentration of electrons grows upon an increase in bromine concentration; however, it is much less than the concentration of the introduced foreign atoms. At x > 0.03, the Fermi level is in the band gap close to the bottom of the conductivity zone at a distance of 0.77 kT, which results in degradation of the semiconductor and constancy of electron concentration and specific electrical conductivity upon a further increase in the dissolved bromine concentration.

Ga Doping of Thin PbTe Films on Si Substrates during Growth

In depositing thin PbTe films onto Si substrates by a modified hot-wall method, Pb1 – xGax melts were used as Ga vapor sources in combination with separate Pb and Te sources. Data on the vaporization behavior of Pb1 – xGax melts were used to devise a new technique for reproducible growth of PbTe/Si and PbTe/SiO2 /Si structures. The lattice parameter of the PbTe films was found to vary nonmonotonically with Ga content, which was interpreted as evidence that the dopant can be incorporated by different mechanisms. Conductivity and Hall effect measurements between 77 and 300 K reveal a nonmonotonic variation of carrier concentration with doping level and suggest that Ga is an amphoteric impurity in narrow-gap IV–VI semiconductors.

Free carrier concentration and conductivity in chlorine doped lead telluride

Plasma resonance in the IR reflection spectra is used to measure the concentration and relaxation time of free charge carriers along with the conductivity in PbTe1 − xClx solid solutions. It is found that with increasing the chlorine concentration, the electron concentration and conductivity increase and reach saturation at x = 0.03 (n = 5.5 × 1019 cm−3, σ = 3750 Ohm−1 · cm−1). The relaxation time decreases with increasing the chlorine concentration and reaches the minimum value of 2.2 × 10−14 s at x = 0.03; then, it almost does not change.

Microdeformations of the crystal lattices of Ga-doped PbTe films on Si substrates

PbTe(Ga) films on Si substrates are obtained from independent sources of tellurium and metal-component vapors by the hot-wall technique. The correlation between the microdeformation of the crystal lattice and the unit-cell parameter is established using an x-ray analysis.

Synthesis of films in the system Ga–Pb with precision control over quantitative composition

According to high-temperature differential mass spectrometry, analytical form of the dependence of structure of the saturated vapor composition over melts of the system Ga–Pb on partial pressures of components and total pressure in the system was determined. On the basis of this dependence, taking into account corrections for the deviations from thermodynamic equilibrium conditions in the reaction cell, the scientifically-proved method of the synthesis of GayPb1–y (y = 0.002–0.050) films with precision control over their quantitative composition structure was developed.