In2O3 : Er films were synthesized on silicon substrates by the RF magnetron sputter deposition. The solid solution ((In1-xErx)2O3) is formed here. The 1.534 µm erbium electroluminescence is observed by the current through the investigated heterostructure substrate-n-Si\In2O3 : Er-film\ITO-contact. The Er excitation model by the electron-hole recombination is proposed as follow. The electron current flows at the indium oxide conduction band. And the hole current flows at the channel in the middle of the In2O3 : Er bandgap. The hole channel is formed by the defect state density spreading from the valence band edge into the bandgap. Therefore the electron-hole recombination energy is lower than the indium oxide bandgap and equals to the 1.56 eV. Then the electron-hole recombination excites in resonance the third excited state of Er3+ 4I9/2 (1.53 eV). Then the nonradiative relaxation to the first excited state 4I13/2 (0.81 eV) occurs. And finally the 1.534 µm radiative emission into ground state 4I15/2 occurs.

Ultrashort pulsed laser annealing is an efficient technique for crystallizing amorphous semiconductors with the possibility to obtain polycrystalline films at low temperatures, below the melting point, through non-thermal processes. Here, a multilayer structure consisting of alternating amorphous silicon and germanium films was annealed by mid-infrared (1500 nm) ultrashort (70 fs) laser pulses under single-shot and multi-shot irradiation conditions. We investigate selective crystallization of ultrathin (3.5 nm) a-Ge non-hydrogenated films, which are promising for the generation of highly photostable nanodots. Based on Raman spectroscopy analysis, we demonstrate that, in contrast to thicker (above 10 nm) Ge films, explosive stress-induced crystallization is suppressed in such ultrathin systems and proceeds via thermal melting. This is likely due to the islet structure of ultrathin films, which results in the formation of nanopores at the Si-Ge interface and reduces stress confinement during ultrashort laser heating.

Monocrystalline silicon (c-Si) (110) sputtering by Xe+ ions with different energies is studied. The microstructure and depth of the subsurface damaged layer arising during ion beam etching have been studied using Raman scattering spectroscopy with excitation by visible and ultraviolet lasers, small-angle x-ray diffraction, and transmission electron microscopy. A threshold dependence of the effect of Xe+ ions energy on the surface roughness during etching has been found. It is shown that ion beam etching induced the intensity enhancement of a broad spectrum around 490-492 cm(-1) originated from the optical mode of phonon near the surface region of c-Si. The origin of this mode was associated with quasi-amorphous Si (q-Si) determined by a shorter correlation length of phonons due to confinement. The roughness of the surface of the c-Si was found to be dependent upon the contribution of the q-Si phase. The depth of the damaged subsurface layer was about 12 nm for etching by Xe+ ions with an energy of 1000 eV, and at an ion energy of 600 eV, the nucleation of a quasi-amorphous phase was observed at a depth of 5-6 nm with preservation of crystallinity below the surface and in volume.

One of the current trends of laser applications in material science is using high-intensity lasers to provide fast and efficient surface or volume modifications for achieving controllable material properties, synthesis of novel materials with desired functionalities, and upscaling laser technologies with industry-demanded throughputs. Depending on the parameters, lasers can offer versatile solutions for scientific and industrial applications, starting from exploring the fundamental physics of warm dense matter and molecular chemistry at ultrashort timescales to large-scale fabrication of surfaces with anti-bacterial, tribological, hydrophobic, or hydrophilic properties. The objectives of this Chapter are to provide a review of recent advancements in several laser application fields, which involve high-intensity lasers, both ultrashort (femto- and picosecond) and short (nanosecond). After summarizing general trends in high-intensity laser processing of materials, we will first focus on the new opportunities offered by high-intensity lasers for the controlled synthesis of multielement nanoparticles for catalytic and theranostic applications. Then, the blister-based laser-induced forward transfer (BB-LIFT) technique will be presented, allowing a one-step, high-precision printing of nanomaterials on any substrates. The next section will discuss the selective crystallization of amorphous (as prepared) semiconductor nanoscale materials. The processes enabling high selectivity of crystallization into the desired phase using ultrashort powerful lasers will be analyzed. After that, opportunities for using high-power lasers will be discussed for upscaling surface nanostructuring with high throughput for bio-medical and industrial applications. Finally, an introduction to the Open Access program of the HiLASE Centre, which is targeted at offering users high-intensity beam time, will be given.

One of the promising materials for opto- and nanoelectronics is nonstoichiometric germanium silicate glass $\left(\text{GeO}_{x}\left[\text{SiO}_{2}\right]\right)$. Composite $\text{GeO}_{x}\left[\text{SiO}_{2}\right]$ films were obtained using co-evaporation of $\text{GeO}_{2}$ and $\text{SiO}_{2}$ powders by electron beams in vacuum and by vapor deposition on a Si substrate. The effect of temperature on the kinetics of Ge nanocluster formation in nonstoichiometric germanium silicate glasses during disproportionation is studied using Raman spectroscopy and Fourier transform infrared absorption spectroscopy. The saturation time of amorphous Ge nanoclusters formation in $\mathbf{G e O}_{\mathbf{x}}\left[\mathbf{S i O}_{\mathbf{2}}\right]$ films is significantly reduced with an increase in the annealing temperature from 400 to $500{ }^{\circ} \mathrm{C}$. Infrared absorption spectra indicate a different disproportionation depth of $\text{GeO}_{x}\left[\text{SiO}_{2}\right]$ films during annealing. The Kolmogorov-Johnson-Mehl-Avrami equation is used to approximate the disproportionation kinetics of $\mathbf{G e O}_{\mathbf{x}}\left[\mathbf{S i O}_{\mathbf{2}}\right]$ films. For the first time, the activation energy of disproportionation for a film of the composition $\left[\text{GeO}_{x}\right]_{0.75}\left[\text{SiO}_{2}\right]_{0.25}$ on a Si substrate was determined, and it equals $0.71 \text{eV} \pm 0.16 \text{eV}$.

The mechanisms of conductivity in metal-insulator-semiconductor (MIS) structures based on [GeOx]((z))[SiO2]((1-z)) films (0.25 <= z <= 1) fabricated by co-evaporation of germanium oxide and silicon oxide powders in vacuum and deposition on a p(+)-type silicon substrate are studied. Indium tin oxide deposited by magnetron method is used as the top electrode. According to IR spectroscopy, Ge-O, Si-O, and Ge-O-Si bonds are detected in the films, while no features related to the presence of germanium clusters are found in the Raman spectra. The current-voltage characteristics (I-V curves) are measured at different temperatures and analyzed by applying the eight most common models of charge transport in MIS structures. It is found that the experimental I-V curves are most accurately approximated in the space charge limited current model, and the parameters of the charge traps are determined within this model.

Electron beam annealing was carried out to form amorphous and crystalline germanium clusters in GeO[SiO] and GeO[SiO2] films deposited on quartz and monocrystalline silicon substrates. Using electron microscopy, Raman spectroscopy, and light transmission and reflection spectroscopy, the structural transformations of the films and their optical properties were studied. From the analysis of Raman spectra, it was shown that amorphous germanium nanoclusters are present in the as-deposited GeO[SiO] film, while they are not observed in the as-deposited GeO[SiO2] film. Regimes of electron beam annealing which are necessary for the formation of germanium nanocrystals in GeO[SiO] and GeO[SiO2] films were found. It was shown that, at the same annealing parameters, the fraction of the crystalline phase of germanium in GeO[SiO] films were smaller than in GeO[SiO2] films. In addition, it was found that the fraction of the crystalline phase at the same annealing parameters is larger for films on a quartz substrate than on monocrystalline silicon substrate. The sizes of germanium nanocrystals formed as a result of electron beam annealing were determined from Raman spectra analysis. The proposed method of obtaining amorphous germanium nanoclusters and nanocrystals in films of nonstoichiometric germanosilicate glasses using electron beam annealing can be used to create ordered arrays of such nanostructures. Keywords: films of nonstoichiometric germanosilicate glass, electron beam annealing, germanium nanoclusters and nanocrystals.

The visible room-temperature emission and excitation photoluminescence spectra were studied as a function of the indium and arsenic profiles in the In+ and As+ ion-implanted thermally grown SiO2 films before and after the annealing at the temperature of 900 degree celsius. As+ ions at the energy of 40 or 135 keV and In+ ions at the energy of 50 keV, providing a projective range ratio R-p(As)/R-p(In) of 1 or 3, respectively, were used. Four emission photoluminescence bands, peaked at similar to 347 nm (3.57 eV), similar to 440 nm (2.81 eV),similar to 450 nm (2.75 eV) and similar to 500 nm (2.48 eV), were obtained from the 40 keV As+ and 50 keV In+ ion-implanted samples under the excitation wavelength of 300 nm (4.13 eV), 350 nm (3.54 eV), 400 nm (3.10 eV) and 450 nm (2.75 eV), respectively. As the As+ energy increased to 135 keV, under the same excitation conditions, the emission bands peaked at 370 nm (3.35 eV), 420 nm (2.95 eV), 460 nm (2.69 eV) and 505 nm (2.45 eV) dominated in the photoluminescence spectra. The excitation spectra of the observed emission peaks were studied, too. We preliminarily interpret the observed photoluminescence peaks as a result of the T-1 -> S-0 transition of molecular-like clusters associated with the oxygen deficiency provided by In or In-As in ion-implanted SiO2.

In this paper, based on the analysis of Raman spectroscopy data, the kinetics of the disproportionation reaction process (GeOx → (1−x/2)Ge + (x/2)GeO2) of an amorphous GeOx film during furnace annealing were studied. An approximation of the experimental kinetics of the disproportionation reaction to the theoretical Kolmogorov–Johnson–Mel–Avrami dependence has been carried out. By analyzing the temperature dependence of the formation time of amorphous germanium clusters, the activation energy of the formation process was obtained, which amounted to 0.9 ± 0.1 eV. In addition, it was found that the position of the Raman peak from amorphous germanium nanoclusters depends on their size. Thus, the phonon localization model can be applied not only to germanium nanocrystals but also to amorphous germanium clusters in the case of their ultra-small sizes (less than 1.5 nm), which is less than the phonon correlation length in amorphous germanium.

The presented paper investigates the formation of nanodiamond structures within multilayer graphene through irradiation with fast heavy ions. The study demonstrates that Xe26+ ions with energies ranging from 26 to 167 MeV can create diamond regions in graphene with lateral sizes ranging from 5 to 20 nm. The density of nanodiamonds formed in the few -layer graphene films is estimated to be approximately (5-30)% of the ion fluence. We show that the final structure of the diamond structures is influenced by factors such as surface orientation, number of graphene layers, and lateral size. Atomistic simulations predicted unusual mechanical properties of the formed 2D composite: its Young's modulus obtained by indentation can significantly exceed the stiffness of the original graphene film.

The results are presented on changes in the parameters of pseudo-MOS transistors based on silicon-on-sapphire (SOS) mesastructures upon irradiation with swift heavy ions (SHIs) of Xe ^+26 (150 MeV) and Bi ^+51 (670 MeV) to a fluence of 2 × 10^11 cm ^-2 , indicating the accumulation of mechanical stresses and charges in the intermediate ferroelectric (Fe) layers of HfO _2 films (HO) with a thickness of 20 nm and Hf _0.5 Zr _0.5 O _2 (HZO) laminated with inserts of Al _2 O _3 monolayers (HA, HZA) or without them. SOS heterostructures are formed by direct bonding and hydrogen transfer of a silicon film (500 nm) with HA and HZA nanolayers pre-applied by plasma-stimulated atomic layer deposition onto sapphire. Electrophysical parameters are determined from the drain current—gate voltage characteristics ( I_ds – V_g) of pseudo-MOS transistors with tungsten drain/source electrodes (100 nm) deposited by magnetron sputtering on SOS mesastructures through a lithographic mask. Comparison of the characteristics with Raman scattering analysis showed the correspondence of the mechanical compressive stresses introduced by SHI irradiation in silicon with the ratios of the Xe and Bi track volumes in the HA ferroelectric and sapphire.

This work is devoted to the study of the influence of controlled Si(111) surface nitridation on the epitaxial growth of AlN-on-Si nucleation layers with reduced tensile stress on ordered crystalline silicon nitride phase. The Si(111) surface nitridation process was performed at low ammonia flux and substrate temperatures in the range of 700-900 degrees C and was studied using RHEED and STM techniques. A universal criterion, namely the stage of the nitridation process completion is introduced, taking into account the influence of substrate temperature, ammonia flux and nitridation time. The 100 nm AlN nucleation layer on silicon substrates grown by ammonia molecular beam epitaxy is studied using AFM, XRD, HR-TEM and Raman spectroscopy techniques. The Raman data show that reducing the nitridation temperature from 900 degrees C to 700 degrees C not only deteriorates the crystalline quality of the subsequent AlN nucleation layers, but also reduces the residual tensile stress by almost 30%. In the present contribution, micro-Raman spectroscopy is used to determine the nature of the defects formed during the high temperature growth of the AlN nucleation layers and confirms them to be inversion domains. The HR-TEM technique was used to study the AlN/Si interface in AlN-on-Si nucleation layers grown on a nitridated silicon surface at 700 degrees C and 900 degrees C at the optimum stage of the nitridation process completion. HR-TEM images of AlN nucleation layers revealed regions with different AlN/Si(111) interfaces: 1) AlN/amorph-Si3N4/Si, 2) AlN/SiN(8 x 8)/Si, and 3) AlN/Si with a sharp interface boundary. Using fast Fourier transform image analysis, it is shown that the presence of amorphous Si3N4 phase inclusions in the AlN/Si interface boundary introduces tensile stresses in the AlN nucleation layer which can be reduced by lowering the nitridation temperature. The results obtained clearly show that one of the causes of cracks in III-nitride layers grown on silicon substrates is the formation of tensile AlN layers with a high content of the amorphous Si3N4 phase at the AlN/Si interface, which is characteristic of silicon nitridation at elevated temperatures (> 700 degrees C).

The effect of annealing time on the InSb nanocrystal formation in a silicon-on-insulator structure, containing, near the Si/SiO2 interface, Si and SiO2 regions implanted with Sb+ and In+ ions, respectively, was studied. The annealing temperature was 1100 degrees C. A change in the nanocrystal growth direction was obtained as the annealing time increased from 1 to 90 min. After the 1 min annealing, the InSb nanocrystals grew within the Si matrix and were faceted. As the annealing time increased to 90 min, the nanocrystals grew from the Si/SiO2 interface into the SiO2 matrix; they had a half-spherical shape. A respective change in the phonon mode was observed, too. The origin of the obtained effect is discussed.

High-quality polycrystalline silicon films on low-cost and low-temperature substrates have attracted much attention as promising materials for high-speed thin-film transistors and thin-film solar cells fabrication. To obtain poly-Si films on low temperature substrates, several concepts have been proposed. Usually the amorphous material undergoes crystallization which can be achieved by various methods including solid-phase crystallization, metal-induced crystallization or liquid-phase crystallization. In this work, we tried to combine the advantages of metal-induced crystallization and liquid-phase crystallization. To achieve this we explored the nanosecond laser crystallization of a bilayer structure consisting of Au and SiO0.1 layers with thicknesses of 30 nm and 130 nm, respectively. The study reveals that when exposed to 532 nm wavelength radiation leads to its destruction due to rupture. On the other hand, when subjected to 1064 nm wavelength radiation, no similar material behavior is observed, and the measured modification threshold is 0.15 J/cm 2 , representing a 40 % reduction compared to SiO0.1 film without gold. It is demonstrated that at laser fluences of 0.35 J/cm 2 and higher, the treated surface in air becomes enriched with silicon dioxide nanoporous coating, attributed to the return of evaporation products to the target surface. Theoretical modeling, assuming thermal evaporation of the coating, suggests that the undesirable nanoporous layer formation can be avoided.

The creation of a new universal nonvolatile memory is one of the most actual problems in nanoelectronics. Recently, it has been believed that memristors are one of the most promising devices for creating such memory. A memristor is a device with two contacts in which it is possible to controllably and reproducibly switch between resistance states by passing current pulses. The search for new materials for memristors is proceeding on a broad front; materials with low bond enthalpy, such as germanium and tin oxides, are promising for reducing switching energy. It is also expected that the use of multilayer structures will help improve the performance of memristors. Nonstoichiometric germanosilicate glass (GeSixOy) films and many-layer structures based on them were deposited using high-vacuum electron beam vapor deposition. The GeO2, SiO, SiO2, or Ge powders were co-evaporated and deposited onto p+-Si(001) substrate (held at room temperature) with resistivity ρ = 0.002 Ω cm. The transparent in visible and near infrared range indium-tin-oxide (ITO) contact was deposited as the top electrode, and memristor metal-insulator-semiconductor (MIS) structures were fabricated. Then the MIS structures were annealed at temperature 500°C. The as-deposited and annealed MIS structures were studied by Fourier-transformed infrared (FTIR) spectroscopy and Raman spectroscopy. The current-voltage characteristics (I–V) and resistive switching cycles of the MIS have been studied. The advantages of GeSixOy based memristors are: low voltage for ON and OFF switching; they do not require a preliminary special “forming” procedure; the appearance of intermediate resistance states, what is perspective for producing of multibit and “analogous” memristors.

The photocurrent in metal -insulator -semiconductor (MIS) structures based on germanosilicate films on n -type silicon with a transparent top electrode made of indium tin oxide has been studied. The first structure contained a GeO[SiO 2 ] layer as a dielectric, and the second structure contained an additional Ge layer 3 nm thick, separated from the silicon substrate by a tunnel -thin layer of SiO 2 . High photosensitivity was obtained for both structures, both as -deposited and after annealing at 500 degrees C for 30 minutes. A mechanism for the generation of photocurrent is proposed, based on the absorption of photons in a depletion region of silicon and tunneling of charge carriers through the dielectric. In the case of the second structure, an additional mechanism for the occurrence of photocurrent associated with the absorption of photons in the Ge layer is assumed. The studied MIS structures can be used in simple, inexpensive photodiodes that do not require the creation of p - n junctions.

It is shown that the nitridation conditions of the silicon substrate are not less important than the structure of the buffer layer in influencing the crack formation in GaN-on-Si layers grown by ammonia-assisted molecular beam epitaxy (NH3-MBE). Furthermore, the morphology of the GaN layers is independent of the buffer layer structure, but is determined by the GaN growth conditions. Nevertheless, the use of step-graded AlGaN buffer layers instead of a buffer layer with an inserted AlN layer leads to a higher crystalline quality of the crack-free GaN layers and to lower residual tensile stresses in them.

MIS structures with a nonstoichiometric oxide dielectric and a transparent top electrode are attracting attention for use as low-cost Schottky-diode-based solar cells, photodetectors, and photomemristors. Previously, attempts were made to use both thin tunnel layers of silicon oxide or rather thick silicon-rich oxides for these purposes. This work is the first attempt to use films of nonstoichiometric germanosilicate films in photosensitive MIS structures.

For the first time, the possibility of producing silicene on CaF2/Si(111) substrates modified by electron irradiation is experimentally demonstrated. It is shown that areas of the planar surface of CaSi2 with hexagonal packing formed under an electron beam can be used as a natural template for the subsequent growth of silicene. Silicon is deposited on such surfaces and the formation of silicene islands is confirmed by atomic force microscopy and Raman spectroscopy.