E S Gorlachev

Investigations of nanocrystalline SnS films' surface morphology modification during inductively coupled argon plasma sputtering

In this work the investigations of the morphology, structure and chemical composition of nanocrystalline SnS films grown by hot wall deposition method on glass substrates before and after high-density low-pressure inductively coupled argon plasma sputtering were performed using scanning electron microscopy, x-ray diffraction analysis, Raman spectroscopy, and energy-dispersive x-ray spectroscopy. The phenomenon of the surface smoothing for the SnS films with petal-like nanocrystallites during plasma treatment is described and the low sputtering rate for the studied films is discussed.

Investigations of the pore formation in the lead selenide films using glacial acetic acid- and nitric acid-based electrolyte

We report a novel synthesis of porous PbSe layers on Si substrates by anodic electrochemical treatment of PbSe/CaF2/Si(111) epitaxial structures in an electrolyte solution based on glacial acetic acid and nitric acid. Electron microscopy, X-ray diffractometry, and local chemical microanalysis investigation results for the porous layers are presented. Average size of the synthesized mesopores with approximately 1010 cm−2 surface density was determined to be 22 nm. The observed phenomenon of the active selenium redeposition on the mesopore walls during anodic treatment is discussed.

Fabrication of porous nanostructured lead chalcogenide semiconductors for modern thermoelectric and optoelectronic applications

Porous structures of lead chalcogenides with porosities of 20-68% and pore dimensions as small as 7-20 nm were fabricated using an anodic electrochemical etching technique applied to epitaxial PbTe and PbSe films on Si. Anodized lead selenide demonstrated two basic types of porous morphology: quasiporous noncontinuous layers and hierarchical porous layers. Lead telluride had a more typical mesoporous morphology, with pores propagating at an angle of 35° to surface, which corresponds to the <100< directions in the epitaxial films and is promising for the fabrication of photonic crystals with Yablonovite-like structure. The sizes of PbTe nanocrystallites in porous layers with high porosity were calculated to be 26 nm, which indicates that quantum confinement conditions are realized in this material. Such low-dimensional morphology of porous lead telluride is prospective for the fabrication of microscale thermoelectric devices with high ZT.

Features of the plasma sputtering of polycrystalline Pb1 − xSnxS films

The processes of the sputtering and modification of surfaces of polycrystalline films of the ternary solid solution Pb1 − xSnxS (x = 0.9–1.0) in a high-density Ar plasma of high-frequency low-pressure inductive discharge are studied. Films with thicknesses of 1–4 μm are grown on glass substrates using the “hot-wall” method and consist of plate-like crystallites. It is established that the sputtering rate for lead-tin sulfide films does not exceed 2.0 nm/s, which is determined by the presence of oxygen-containing compounds on the surfaces. In the case of plate-like crystallites with nanodimensional thicknesses, the effect of smoothing of the developed surfaces of the polycrystalline Pb1 − xSnxS layers during plasma treatment is observed; this is important for fabricating multilayer device structures.

Investigations of the inductively coupled argon plasma sputtering of Pb1 − xSnxTe ternary solid solution

Investigations of the sputtering of films of the Pb1 − xSnxTe ternary solid solution with 0 ≤ x ≤ 1 in RF high-density low-pressure inductively coupled argon plasma have been performed. The effect of a constant sputtering rate with variation in the composition of the semiconductor solid solution for (111)-oriented films with x < 0.6 and of a sputtering rate decrease with the appearance of (100)-oriented crystallites at x > 0.6 is found. The results are analyzed in the context of a model of ternary alloy sputtering based on the Sigmund solid sputtering theory when taking into account the sublimation energies of binary compounds that constitute a solid solution.

Lead selenide nanowire growth by vapor-liquid-solid mechanism under mask during plasma processing

Data on the formation of lead selenide (PbSe) nanowires under a stencil mask during the processing of epitaxial PbSe films in high-density inductively coupled plasma (ICP) of low-pressure argon RF discharge are presented. The nanowires were studied by high-resolution scanning electron microscopy and energy-dispersive X-ray spectroscopy. A physical model is proposed that explains the local formation of PbSe nanowires in terms of their catalytic growth according to the vapor-liquid-solid mechanism.

Application of abnormally high sputtering rate of PbTe(Te) single crystals during inductively coupled argon plasma treatment for fabrication of nanostructures

This paper reports the investigations of the sputtering process of (111) oriented single crystals of PbTe with excess tellurium (4 at.%) in RF high-density low-pressure inductively coupled argon plasma. An increase of 1.6 times the sputtering rate of lead telluride in comparison with the classical case of single-crystal state with a slight deviation from stoichiometry is shown and the explanation of the results is carried out based on the analysis of the crystal point defects. The active sputtering is used in a new approach to form lead telluride nanostructures on oxidized Si substrates via the vapour–liquid–solid (VLS) redeposition mechanism, and the fabrication of PbTe nanocones, nanocubes and nanowires with various geometrical parameters is demonstrated.

Plasma sputtering of polycrystalline Pb1−x Sn x Te thin films grown on glass substrates using hot wall deposition

In this work the investigations of the argon inductively coupled plasma sputtering of the Pb1−x Sn x Te thin films with the composition variation of x = 0.16–0.95 grown by hot wall deposition technique on glass substrates were carried out. As-grown films had a columnar polycrystalline structure with the grain lateral dimensions of 0.2–5.0 μm, and the dependence of the lattice constant on composition x had a linear behaviour described by the Vegards law. Energy dispersive x-ray microanalysis showed the presence of 5–8 at.% of oxygen in the films, which can be accumulated from the ambient air or from the substrate in the inter-grain boundaries. A phenomenon of a sputtering rate decrease for the polycrystalline lead tin telluride films in comparison to the single-crystal films is discussed. A novel important phenomenon of the formation of nanostructure arrays on the surface of the Pb1−x Sn x Te thin films with the dependence on the sputtering rate during plasma treatment is reported.

Investigations of nanostructured porous PbTe films with x-ray diffractometry and reflectometry

In this work application of x-ray total external reflection method for the determination of the porosity value of PbTe and PbSe epitaxial films on silicon substrates subjected to anodic electrochemical etching in a Norr electrolyte was carried out. It is shown that the porosity values of the films can be in the range of 10-68% depending on the anodizing conditions. Triple-crystal x-ray diffractometry method was utilized for the estimation of quantitative characteristics of the pore dimensions along different directions. Nanometer-range pore dimensions and shape are estimated.

Plasma sputtering of Pb1–xEuxTe films with varied composition and structure

We investigate the sputtering of single-crystal and polycrystalline films of Pb1–xEuxTe (x = 0.02–0.10) in high-frequency inductively coupled argon plasma. Layers of Pb1–xEuxTe are grown via molecular beam epitaxy on barium-fluoride substrates of the (111) orientation at 340 and 200°C. For single-crystal films, the dependence of the sputtering rate on the europium concentration is found. For polycrystalline layers, a decrease in the sputtering rate is observed. This is caused by the effect of europium oxidation at the surface of the polycrystallites.