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.

The measurements of sputtering etch rates for monocrystalline (1 1 1)-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(1 1 1) and BaF 2 (1 1 1) 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.

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In this work, we report a novel approach to the surface nanostructuring of lead tin telluride films using inductively coupled argon plasma treatment with the average ion energy of 200 eV and the duration of 20-60 s. The nanostructuring was carried out on the plasma treated surface of epitaxial single-crystal Pb 1−x Sn x Te films grown on BaF 2 (111) substrates using molecular beam epitaxy. The plasma treatment of the surface of the Pb 1−x Sn x Te films with the low and medium Sn content (x=0-0.6) resulted in the formation of the arrays of 'capped' conical nanostructures with the height up to 420 nm, depending on the Sn content and treatment duration, and the surface density of ∼10 9 cm −2 . The plasma treatment of the surface of the films with the high Sn content (x=0.8-1) yielded the formation of a second group of flat nanostructures without 'caps', which had necklace-like rings consisting of multiple nanodroplets around their rims. Using transmission electron microscopy, we show that the quasi-spherical droplet 'caps' of the nanostructures consist of Pb 'wrapped' in Sn. We explain the physical mechanism of the observed plasma-assisted nanostructure self-formation in the framework of the multi-stage model including physical sputtering, redeposition, vapour-liquid-solid mechanism and micromasking mechanism.

In this work investigations of sputtering of monocrystalline (1 1 1)-oriented epitaxial films of semiconductor ternary solid solutions of Pb 1−x Sn x Te (x = 0.00-0.56), Pb 1−x Eu x Te (x = 0.00-0.05), Pb 1−x Sn x Se (x = 0.00-0.07), Pb 1−x Eu x Se (x = 0.00-0.16, x = 1.00), Pb 1−x Sn x S (x = 0.00-0.05) on Si(1 1 1) and BaF 2 (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.