Formation of SnO and SnO2 phases during the annealing of SnO(x) films obtained by molecular beam epitaxy

SnO and SnO2 films were obtained on the SiO2 surface by the molecular-beam epitaxy method. The initial film

Elastically stressed pseudomorphic SiSn island array formation with a pedestal on the Si(1 0 0) substrate using Sn as a growth catalyst

The Sn-rich islands with a Si pedestal on the Si(1 0 0) substrate were obtained by the molecular-beam epitaxy technique. Initially, Sn films of different thicknesses were formed on the Si surface and then annealed to create the Sn island arrays, which were used as nanoobject growth catalysts. The Sn island density reaches up to 6 × 109 cm−2, whereas the Sn island sizes are changed in the range of 40–180 nm. The Sn-rich islands with the Si pedestal were first appeared after the Si deposition on the surface with the Sn islands in the temperature range of 300–450 °C. The new obtained nanostructures have the island density up to 4 × 108 cm−2 and the island sizes, which varied from 60 to 400 nm. The island growth with the pedestal occurred on the vapor-liquid-solid mechanism. The chemical analysis of the samples carried out using the energy-dispersive X-ray spectroscopy indicated the presence of the Sn-rich region on the top of nanoobjects. The intense photoluminescence from the Sn-rich islands with the Si pedestal was detected. The photoluminescence peak takes place at 1.55 µm

Morphology, structure, and optical properties of semiconductor films with GeSiSn nanoislands and strained layers

The dependences of the two-dimensional to three-dimensional growth (2D-3D) critical transition thickness on the composition for GeSiSn films with a fixed Ge content and Sn content from 0 to 16% at the growth temperature of 150 °С have been obtained. The phase diagrams of the superstructure change during the epitaxial growth of Sn on Si and on Ge(100) have been built. Using the phase diagram data, it becomes possible to identify the Sn cover on the Si surface and to control the Sn segregation on the superstructure observed on the reflection high-energy electron diffraction (RHEED) pattern. The multilayer structures with the GeSiSn pseudomorphic layers and island array of a density up to 1.8 × 1012 cm−2 have been grown with the considering of the Sn segregation suppression by the decrease of GeSiSn and Si growth temperature. The double-domain (10 × 1) superstructure related to the presence of Sn on the surface was first observed in the multilayer periodic structures during Si growth on the GeSiSn layer. The periodical GeSiSn/Si structures demonstrated the photoluminescence in the range of 0.6–0.85 eV corresponding to the wavelength range of 1.45–2 μm. The calculation of the band diagram for the structure with the pseudomorphic Ge0.315Si0.65Sn0.035 layers allows assuming that photoluminescence peaks correspond to the interband transitions between the X valley in Si or the Δ4-valley in GeSiSn and the subband of heavy holes in the GeSiSn layer

Growth of epitaxial SiSn films with high Sn content for IR converters

Growth of SiSn compounds with a Sn content from 10 to 35% is studied. The morphology and surface structure of the SiSn layers are examined and the kinetic diagram of the morphological state of SiSn films is established in the temperature range of 150–450°C. During the growth of SiSn films from 150 to 300°C, oscillations of specular beam were observed. For the first time, periodic multilayer SiSn/Si structures with pseudomorphic monocrystalline SiSn layers with the Sn content from 10 to 25% are grown. The c(8×4) and (5×1) superstructures are identified during the growth of Si on the SiSn layer and the conditions are determined for the formation of the desired Si surface structure by controlling the growth temperature. From the diffraction reflection curves, the lattice parameter, the SiSn composition, and the period in the multilayer periodic structure are defined, which with high precision correspond to the specified values

Growth of epitaxial SiSn films with high Sn content for IR converters

Growth of SiSn compounds with a Sn content from 10 to 35% is studied. The morphology and surface structure of the SiSn layers are examined and the kinetic diagram of the morphological state of SiSn films is established in the temperature range of 150–450°C. During the growth of SiSn films from 150 to 300°C, oscillations of specular beam were observed. For the first time, periodic multilayer SiSn/Si structures with pseudomorphic monocrystalline SiSn layers with the Sn content from 10 to 25% are grown. The c(8×4) and (5×1) superstructures are identified during the growth of Si on the SiSn layer and the conditions are determined for the formation of the desired Si surface structure by controlling the growth temperature. From the diffraction reflection curves, the lattice parameter, the SiSn composition, and the period in the multilayer periodic structure are defined, which with high precision correspond to the specified values

Effect of Sn for the dislocation-free SiSn nanostructure formation on the vapor-liquid-crystal mechanism

Structures with tin-rich island arrays on silicon pedestals were obtained by molecular beam epitaxy using Sn as a catalyst for the growth of nanostructures. A tin island array was used further to study the growth of nanostructures in the process of Si deposition on the surface with Sn islands. It was established that, during the growth on the vapor-liquid-crystal mechanism, tin-rich islands are formed on faceted pedestals. A nanostructured cellular surface was formed between the islands on pedestals. The analysis of the elemental composition of the obtained nanostructures was performed by the methods of energy dispersive X-ray spectroscopy and photoelectron spectroscopy. It is shown that tin-rich islands can contain up to 90% tin, whereas the pedestal consists of silicon. The transmission electron microscopy data demonstrated a distinct crystal structure of tin-rich islands and silicon pedestals, as well as the absence of dislocations in the structures with island arrays on the faceted pedestals. The facet tilt angle is 19° and corresponds to the (311) plane. The photoluminescence signal was observed with a photoluminescence maximum near the wavelength of 1.55 μm

Elastically strained GeSiSn layers and GeSiSn islands in multilayered periodical structures

This work deals with elastically strained GeSiSn films and GeSiSn islands. The kinetic diagram of GeSiSn growth for different lattice mismatches between GeSiSn and Si has been drawn. The multilayered periodic structures with pseudomorphic GeSiSn layers and GeSiSn island arrays have been obtained. The density of the islands in the GeSiSn layer is 1.8 · 1012 cm-2 for an average island size of 4 nm. Analysis of the rocking curves has shown that the structures contain smooth heterointerfaces, and no abrupt changes of composition and thickness between periods have been found. Photoluminescence has been demonstrated and calculation of band diagram with the model-solid theory has been carried out. Luminescence presented for sample with pseudomorphic Ge0.315Si0.65Sn0.035 layers in the narrow range 0.71–0.82 eV is observed with the maximum intensity near 0.78 eV corresponding to 1.59 µm wavelength. Based on the band diagram calculation for Si/Ge0.315Si0.65Sn0.035/Si heterocomposition we have concluded that 0.78 eV photon energy luminescence corresponds to interband transitions between the X-valley in Si and the heavy hole subband in the Ge0.315Si0.65Sn0.035 layer

Morphology, structure, and optical properties of SnO (x) films

The paper presents the morphological, structural, and optical properties of nanostructured SnO (x) film

Effect of annealing temperature on the morphology, structure, and optical properties of nanostructured SnO(x) films

Fabrication and characterization of titanium dioxide (TiO2) thin film on Al/TiO2/SiO2/p-Si MIS structure for the study of morphology, optical and electrical properties were reported. A transparent and high crystallinity of TiO2 thin films were prepared at room temperature (~25 °C) by sol–gel route. TiO2 sol suspension were prepared at molar ratio of TTIP:EtOH:AA = 2:15:1 using titanium tetra-isopropoxide (TTIP) and a mixture of absolute ethanol (EtOH) and acetic acid (AA) which used as a precursor and catalyst for the peptization, respectively. The TiO2 thin films were deposited on a thermally grown SiO2 layer of p-type silicon (100) substrates and were thermally treated at different annealing temperatures of 300, 500, 700 and 900 °C. For study of optical properties, the TiO2 thin films were deposited on a glass slides substrate and were annealed from 200 to 700 °C. The XRD results show that the presence of an amorphous TiO2 phases were transformed into the polycrystalline (anatase or rutile) with good crystallinity after treated at higher annealing temperatures. Besides, the surface roughness of TiO2 thin films increased with increasing annealing temperatures. In addition, the resistivity of the thin films decreased from 2.5751E+8 to 6.714E+7 Ω cm with the increasing temperatures. Moreover, the optical absorbance of TiO2 thin films exhibited high UV–visible light absorption with band gap energy shifted to the higher wavelength (low energy photons). The band gap energy (Eg) of the films decreased from 3.79 to 3.16 eV and from 3.95 to 3.75 eV significantly for direct band allowed and indirect band allowed, respectively, with the increasing annealing temperatures