I. I. Amirov

Micromasking effect and nanostructure self-formation on the surface of lead chalcogenide epitaxial films on Si substrates during argon plasma treatment

The surface modification of lead chalcogenide epitaxial films during plasma treatment processes is investigated. With AFM and SIMS measurements it was shown that the mechanism of a microhillock formation is the micromasking effect of dislocation exit sites. Micromasking, and hence microhillock formation, takes place when fluorine sputtered from reactor chamber walls is present on the surface of the films. Micromasks are nucleated at the exits of threading dislocations when low-volatile fluoride compounds are formed due to the reaction of atomic fluorine with Al or Pb accumulated in these areas. The effects obtained are analysed from the standpoint of nanostructure formation, which requires, primarily, the suppression of the micromasking effect. A novel method of fabricating lead chalcogenide nanostructures on Si(1 1 1) substrates via Ar plasma treatment is proposed.

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.

RF sputtering of epitaxial lead chalcogenide films in argon and krypton plasma

The measurements of sputtering etch rates for monocrystalline (111)-oriented epitaxial films of semiconductor binary compounds PbTe, PbSe, PbS in RF high-density low-pressure inductively coupled argon and krypton plasma were performed. Films with 1‐5 μm thickness were grown on Si(111) and BaF2(111) substrates using molecular beam epitaxy. Sputtering was carried out with the energy of Ar + and Kr + ions of 20‐400 eV. The sputtering etch rates of the binary lead chalcogenides are demonstrated to have abnormally high values in comparison with the basic semiconductor materials of microelectronics. The sputtering yield values for PbTe, PbSe, PbS for the average energy of the argon ions of 200 eV are practically equal (0.46 ± 0.05 molecule/ion) and vary linearly with the variation of the ion energy. Substitution of the plasma discharge gas from the argon to krypton does not result in a significant change in the sputtering yield of lead chalcogenides. The physical principles of the observed phenomena are discussed.

Sputtering rates of lead chalcogenide-based ternary solid solutions during inductively coupled argon plasma treatment

In this work investigations of sputtering of monocrystalline (1 1 1)-oriented epitaxial films of semiconductor ternary solid solutions of Pb1−xSnxTe (x = 0.00–0.56), Pb1−xEuxTe (x = 0.00–0.05), Pb1−xSnxSe (x = 0.00–0.07), Pb1−xEuxSe (x = 0.00–0.16, x = 1.00), Pb1−xSnxS (x = 0.00–0.05) on Si(1 1 1) and BaF2(1 1 1) substrates in RF high-density low-pressure inductively coupled argon plasma were carried out. It is determined that sputtering rates for the studied materials retain high values typical for binary solutions PbTe, PbSe, PbS. The results indicate the interrelation of the sputtering rates of ternary compounds and of the sublimation energy of binary compounds that constitute a solid solution. The physical model of this characteristic property of lead chalcogenide-based ternary alloys based on the expansion of a classic Sigmund solid sputtering theory explaining the observed sputtering rate behavior with the alloy composition variation is proposed.

Role of threading dislocations during treatment of PbTe films in argon Plasma

Epitaxial n-PbTe films grown on CaF2/Si(1 1 1) wafers using MBE were treated in an inductively coupled high-density Ar-plasma for a time period of 30 s. AFM measurements showed that after the treatment process large hillocks, 350–450 nm high, are formed on the dislocation exit sites. The tips of the hillocks have triangular dislocation exit pits. The density of the large hillocks corresponds to the dislocation density on the initial surface.

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.

Simulation of the effects of deep grooving in silicon in the plasmochemical cyclic process

The results of computer simulation of the effects of the formation of deep groove profiles in silicon during the cyclic etching-passivating process in SF6/C4F8 plasma are reported. It is shown that the groove profile varies under variations in one of the basic parameters of the process, the etching-passivation time ratio at different probabilities of the reactions of etching and the deposition of a fluorocarbon film. The sensitivity of the model to these parameters is determined. Grooves with different tilt angles of walls are simulated, and the opportunity for controlling the groove profile by varying the parameters during grooving is shown.

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.