Search

It is shown that self-forming GeSi nanoislands built into the dielectric–semiconductor interface in the Si(001)-based metal–oxide–semiconductor (MOS) structures with the SiOx and ZrO2(Y) dielectric layers obtained by magnetron sputtering initiate bipolar resistive switching without preliminary electroforming. The I–V characteristics and electrical parameters of the MOS structures in the high- and low-resistance states have been investigated. The change in the charge incorporated in the dielectric at the dielectric–semiconductor interface during resistive switching has been established, which is related to the formation and destruction of conducting filaments. The optically stimulated switching of the MOS structures with the ZrO2(Y) dielectric layer from the high- to low-resistance state has been observed, which is caused by an increase in the conductivity of the space charge region in the Si substrate due to the interband optical absorption in Si leading to the voltage redistribution between Si and ZrO2(Y). A difference between the shapes of the low-signal photovoltage spectra of the MOS structures in the spectral region of the Si intrinsic photosensitivity in the high- and low-resistance states related to the leakage of photoexcited carriers from Si into a metal electrode through filaments has been found.

The specific features of resistive switching, which was initiated by triangular pulses with a high-frequency sine signal imposed on them, in experimental memristor prototypes based on thin films of yttria-stabilized zirconia were examined. It was found that memristors switched by these complex signals have lower switching voltage, higher ratio of currents in low- and high-resistance states, and better long-term current stability than memristors switched by triangular pulses without the sine signal. This improvement of switching parameters is associated with resonance activation of migration of oxygen ions via vacancies in the alternating external electric field.

The electrophysical characteristics of a multilayer memristive Au/Ta/ZrO2(Y)/TaOx/TiN structure have been studied. Electron and ion electret effects due to charge carrier trapping and ion migration polarization in the dielectric have been discovered. The influence of traps on electroforming processes and resistive switching has been established. The values of activation energy and ion and trap concentrations have been determined. The effect of resistive switching stabilization has been found, which is associated with the specific bilayer structure of TaOx and self-forming tantalum nanoclusters. The nanoclusters serve as electric field concentrators in the course of electroforming and subsequent resistive switching.

The Ag/Ge/Si(001) stacks with threading dislocations growing through the Ge epitaxial layers (ELs) manifested bipolar resistive switching (RS) between two metastable resistance states. Scanning transmission electron microscopy (STEM) provided a direct evidenced the RS mechanism to consist in the electrodiffusion of Ag+ ions along the dislocations in the Ge ELs. Also, STEM revealed multiple RS cycling to result in the metallization of the Ge matrix around the dislocations and in the accumulation of Ag in the misfit dislocation layer near Ge/Si interface. Both above phenomena may lead potentially to degradation of the RS performance.

Local resistive switching by complex nonstationary signals in zirconium-dioxide-stabilized films on conducting substrates has been studied by atomic-force microscopy with a conducting probe. Film resistance was switched by triangular voltage pulses on which a high-frequency sinusoidal signal was superimposed. It is found that the ratio of currents through the junction between the probe and film surface in high-resistance and low-resistance states increases after the superposition of a sinusoidal signal (as compared to switching by simple triangular pulses). An increase in the temporal stability of the current strength in these states was also found when switching with a sinusoidal signal. This effect is associated with resonant activation of oxygen ion migration over vacancies in an external ac electric field.

The peculiarities of resistive switching in capacitors with yttria-stabilized hafnia layers were studied. The characteristics of current transport in the initial state and after electroforming and resistive switching at different temperatures were examined. The parameters of a small-signal equivalent circuit of a capacitor were determined for switching into low- and high-resistance states. These parameters suggest that the resistance of filaments changes after each successive switching. This provides an opportunity to use such measurements to determine the nature of resistive switching and verify the reproducibility of its parameters. The contribution of electron traps to switching was revealed. Ion migration polarization was observed at temperatures above 500 K, and the activation energy of ion migration and the ion concentration were determined. The effect of resistive switching under the influence of temperature was observed and interpreted for the first time.

The local transverse photoconductivity of ultrathin (~4 nm) ZrO2(Y) films with embedded single-layer arrays of Au nanoparticles (~2 nm in diameter) is studied by conductive atomic force microscopy. The ZrO2(Y) films with Au nanoparticles are formed on glass substrates with transparent conductive indium-tin-oxide sublayers using layer-by-layer magnetron deposition followed by annealing. The peaks observed in the optical absorption spectra of the samples at the wavelength λ ≈ 660 nm are attributed to collective plasmon resonance in dense arrays of Au nanoparticles. The photocurrent between the microscope probe and the indium-tin-oxide sublayer is measured during photoexcitation of the contact between the probe and the sample surface through the transparent substrate by the radiation of a semiconductor laser diode at the plasmon-resonance wavelength. The increase in current through the probe of the atomic force microscope under photoexcitation is attributed to the photon-assisted emission of electrons from the Au nanoparticle into the conduction band of ZrO2(Y) in a strong electric field applied between the probe and the indium-tin-oxide sublayer under plasmon resonance conditions.

Ag/Ge/Si heterostructures with threading dislocations in Ge layer can exhibit resistive switching (RS) in two regimes: (i) bipolar and (ii) volatile unipolar. In both regimes, these structures possess stable states with the ratio of currents in the low-resistance state (LRS) and high-resistance state (HRS) within 1.5–2.7. The volatile unipolar switching can be determined by capturing charge carriers on deep levels related to misfit dislocations at the Ge/Si interface, whereas the bipolar switching is related to the drift of Ag+ ions via threading dislocations.

The effect of the material of the metal plates (Au, Ta, W) and exposure to a high-power blue laser on the memristive characteristics of metal–insulator–semiconductor (MIS) capacitors with a Si3N4 film 6 nm thick fabricated on the basis of n+-Si is studied. It is shown that bipolar switching by the current appears only in capacitors with Au. The causes of the absence of bipolar switching in capacitors with Ta and W are explained. The switching of capacitors with Ta by the current and light and the photomemory effect are detected. It is shown that, despite the high doping level of the semiconductor substrate, it decreases the MIS memristor response rate due to a high density of surface states localized at the Si3N4/n+-Si interface. However, illumination allows a significant increase in the response rate due to a decrease in the semiconductor resistivity. The surface state densities are determined. To improve the frequency characteristics of MIS memristors, it is necessary to achieve a low surface state density.

The effect of optical illumination on the resistive switching in ultrathin (~4 nm) ZrO2(Y) films with embedded single-layer Au nanoparticle arrays 2–3 nm in size is studied via tunneling atomic force microscopy. The ZrO2(Y) films with Au nanoparticles are grown by layerwise magnetron deposition onto glass substrates with a conductive indium-tin-oxide sublayer, followed by annealing at 450°C. An increase in hysteresis due to bipolar resistive switching in the ZrO2(Y) films is observed on the cyclic current–voltage curves of the microscope probe-to-sample contact. The effect is found to manifest itself in a dense Au nanoparticle array (~660 nm) when the contact area is photoexcited through a transparent substrate exposed to the radiation of a semiconductor laser at the plasmon-resonance wavelength. The effect is attributed to the photon-assisted field emission of electrons from Au nanoparticles to the conduction band of ZrO2(Y) in a strong electric field between the microscope probe and the indium-tin-oxide substrate under plasmon-resonance conditions.

Resistive switching and adaptive behavior of resistive state in response to electrical stimulation has been studied for the silicon oxide based memristive devices subjected to electroforming in the conditions of current compliance in comparison with the analogous memristive devices after electroforming without any current limitation. The limitation of current and temperature during electroforming affects the parameters of growing conductive filament ensembles and reduction-oxidation reactions resulting in a gradual character and a wide dynamic range of resistance change important for neuromorphic applications.

Bipolar resistive switching of the metal-insulator-semiconductor (MIS) capacitor-like structures with the inert Au top electrode and Si3N4 dielectric nanolayer (6 nm thick) has been investigated. The effect of highly doped n+-Si substrate is revealed related to the changes in semiconductor space charge region on the small-signal parameters of parallel and serial equivalent circuit models measured in the high- and low-resistive capacitor states, as well as under laser illumination. The increase in conductivity of semiconductor capacitor plate significantly reduces the charging and discharging times of capacitor-like structures.

Planar waveguides based on tungsten-tellurite glasses doped with erbium and ytterbium ions are created. Planar structures with a superimposed strip based on tungsten tellurite glasses were formed by methods of Radio Frequency Magnetron Sputtering and lithography. Waveguide operation up to 1.53 mkm was observed. Optical losses at a wavelength of 1.53 mkm in the test channel waveguides with a width of 15 μm are ~ 0.44 dB/cm. The dependence of the optical signal enhancement at a wavelength of 1.53 mkm on the pump power was investigated for different lengths of waveguide.

It has been experimentally established that the time of switching by triangular pulses in Ti—TiN–ZrO2(Y)–Zr–Au memristor structures from the state of low resistance to the state of high resistance is inversely proportional to the voltage rise rate, i.e., the bias current through the memristor structure. A mechanism for the influence of a bias current on the switching time of the structure has been proposed.

Local resistive switching (RS) in ZrO2(Y) films on conductive substrates has been studied using Conductive Atomic Force Microscopy (CAFM). Switching was performed by triangle voltage pulses with superimposed a high-frequency (HF) sinusoidal signal applied to the contact of the CAFM probe to the ZrO2(Y) film (together constituting a nanometer-sized virtual memristor). Earlier, the enhancement of the RS performance has been observed when the HF signal was superimposed onto the switching pulses. The effect was attributed to the resonant activation of the migration of oxygen ions via oxygen vacancies by an external alternating electric field. In the present study, this assumption was confirmed by measuring the frequency dependence of the difference between the probe currents in the low-resistance and high-resistance states with a maximum at about 5 kHz. This frequency corresponds to the characteristic one of the jumps of oxygen ions onto adjacent oxygen vacancies in ZrO2(Y) at 300 K. The experimental results were compared with the results of simulation based on the Chua model of an ideal memristor.

It is shown that the formation of Au nanoparticles at the insulator–silicon interface in structures with a high density of surface states results in a shift of the Fermi-level pinning energy at this interface towards the valence-band ceiling in silicon and in increasing the surface-state density at energies close to the Fermi level. In this case, a band with a peak at 0.85 eV arises on the photosensivity curves of the capacitor photovoltage, which is explained by the photoemission of electrons from the formed Au-nanoparticle electron states near the valence-band ceiling in silicon.

The properties of metal–insulator–semiconductor (MIS) structures based on n-GaAs in which silicon oxide and yttria-stabilized zirconia and hafnia are used as the insulator containing InAs quantum dots, which are embedded at the insulator/n-GaAs interface, are investigated. The structures manifest the resistive switching and synaptic behavior.

The change of the immitance of the metal–insulator–metal memristive structures based on SiOx, which is observed during electroforming and resistive switching, confirms the formation of conducting channels (filaments) in the insulator during forming and their rupture upon a transition of the structure to a highresistance state. The observed switching of the differential capacitance and conductivity synchronously with the switching of current (resistance) can substantially extend the functional applications of memristive devices of this type.

We have studied Au/SiOx/TiN/Ti memristive structures obtained by magnetron sputtering, which exhibit a reproducible resistive switching effect. The influence of the thickness and stoichiometry of SiOx layer and the area of Au electrode on the parameters of switching has been analyzed. The obtained results show evidence in favor of the filament model of resistive switching in SiOx films.

The Ag/Ge/Si(001) stacks with threading dislocations in Ge layer demonstrating the I-V curves typical for the bipolar resistive switching were investigated. Cross-sectional transmission electron microscopy and electron beam induced current measurement confirmed the resistive switching mechanism to be the formation of conductive filaments consisting of the Ag atoms across the entire Ge layer via the electric-field driven transport of Ag+ ions along the threading dislocations.

We report on a comparative study of resistive switching in the memristors based on ZrO2(Y) films and on ZrO2(Y)/Ta2O5 bilayer stacks by triangle voltage pulses with superimposed high-frequency sinusoidal signal. The dependencies of the current difference in the low resistance state and in the high resistance one on the sinusoidal signal frequency for the ZrO2(Y)-based memristor and for the ZrO2(Y)/Ta2O5-stack based one manifested one and two maxima, respectively attributed to the resonant activation of the migration of the oxygen ions via the oxygen vacancies by the alternating external electric field in ZrO2(Y) and in Ta2O5.

Resistive switching (RS) is studied in a memristor based on a ZrO2(Y)/Ta2O5 stack under a white Gaussian noise voltage signal. We have found that the memristor switches between the low resistance state and the high resistance state in a random telegraphic signal (RTS) mode. The effective potential profile of the memristor shows from two to three local minima and depends on the input noise parameters and the memristor operation. These observations indicate the multiplicative character of the noise on the dynamical behavior of the memristor, that is the noise perceived by the memristor depends on the state of the system and its electrical properties are influenced by the noise signal. The detected effects manifest the fundamental intrinsic properties of the memristor as a multistable nonlinear system.

The low-frequency noise in a nanometer-sized virtual memristor consisting of a contact of a conductive atomic force microscope (CAFM) probe to an yttria stabilized zirconia (YSZ) thin film deposited on a conductive substrate is investigated. YSZ is a promising material for the memristor application since it is featured by high oxygen ion mobility, and the oxygen vacancy concentration in YSZ can be controlled by varying the molar fraction of the stabilizing yttrium oxide. Due to the low diameter of the CAFM probe contact to the YSZ film (similar to 10nm), we are able to measure the electric current flowing through an individual filament both in the low resistive state (LRS) and in the high resistive state (HRS) of the memristor. Probability density functions (Pdfs) and spectra of the CAFM probe current in both LRS and HRS are measured. The noise in the HRS is found to be featured by nearly the same Pdf and spectrum as the inner noise of the experimental setup. In the LRS, a flicker noise 1/f(gamma) with gamma approximate to 1.3 is observed in the low-frequency band (up to 8kHz), which is attributed to the motion (drift/diffusion) of oxygen ions via oxygen vacancies in the filament. Activation energies of oxygen ion motion determined from the flicker noise spectra are distributed in the range of [0.52; 0.68] eV at 300K. Knowing these values is of key importance for understanding the mechanisms of the resistive switching in YSZ based memristors as well as for the numerical simulations of memristor devices.

We have studied light-induced resistive switching in metal–insulator–semiconductor structures based on silicon covered with a tunneling-thin SiO2 layer and nanometer-thick layer of antimony. The role of an insulator was played by yttria-stabilized zirconia.

We report on the investigation of the resistive switching (RS) in the ultrathin (≈5 nm in thickness) yttria-stabilized zirconia (YSZ) films with single layers of Au nanoparticles (NPs) by conductive atomic force microscopy (CAFM). Besides the butterfly-type hysteresis loops in the current-voltage (I-V) curves of the contact of the CAFM probe to the investigated film surface corresponding to the bipolar RS, the negative differential resistance (NDR) has been observed in the I-V curves of the AFM probe contact to the YSZ films with Au NPs in the conductive (“ON”) state. The NDR has been related to the resonant tunneling of electrons through the size-quantized energy states in the ultrafine (1 to 2 nm in diameter) Au NPs built in the conductive filaments in the YSZ films.

We report the investigations of the ion migration polarization in the yttria stabilized zirconia (YSZ) thin films in the Metal-Oxide-Metal (MOM) and Metal-Oxide-Semiconductor (MOS) stacks due to the drift of the oxygen vacancies under the external bias voltage applied between the electrodes. The parameters characterizing the drift of the oxygen vacancies in YSZ such as the ion drift activation energy, mobile ion concentration, and the drift mobility have been determined in the temperature range 300–500 K. These data are important for deeper understanding of the fundamental mechanisms of the electroforming and resistive switching in the YSZ-based MOM and MOS stacks, which are promising for the Resistive Random Access Memory (RRAM) and other memristor device applications.

The effect of resistive switching in the yttria stabilized zirconia (YSZ) thin films on Si substrates has been studied by Conductive Atomic Force Microscopy (CAFM). The resistive switching of the YSZ films from the low conductive state to the highly conductive one has been found to be associated with the increasing of the noise with broad frequency spectrum related to the redistribution of the oxygen vacancies in YSZ. The electrical oscillations in oscillation loop connected in series to the CAFM probe, the sample, and the bias source related to the excitation of the oscillation loop by the noise in the probe-to-sample contact film have been observed. The effect discovered is promising for application in the memristor devices of new generation.

Using as an example metal-insulator-semiconductor structures based on GaAs with stabilized (by yttrium oxide) zirconium dioxide, which show the effect of resistive-switching random-access memory, the possibility is considered of controlling phenomena associated with the forming process in the insulator and on the insulator-semiconductor interface, as well as in the semiconductor, by measuring the response of the semiconductor.

Contact photolithography was used to fabricate three-layer polymeric waveguide structures with transverse dimensions of 50 × 90 μm on the basis of two photopolymerizing methacrylate compositions with different refractive indices. The optical loss on the wavelength of 632.8 nm was 0.37 ± 0.14 dB cm−1. This loss is mostly due to the light scattering by the material of the waveguide layer produced by bulk polymerization.

Resistive switching in the yttria stabilized zirconia films on the conductive substrates has been studied using Conductive Atomic Force Microscopy. Switching was performed by triangle voltage pulses with superimposed high-frequency sinusoidal signal applied between the probe and the sample. The performance of the resistive switching was characterized quantitatively by the ratio of the electric current flowing through the contact of the probe to the dielectric film surface (together constituting a nanometre-sized virtual memristor) in the low resistance state and in the high resistance one (ON/OFF ratio). The increase in this ratio when applying the sinusoidal signal as compared to the switching by the triangle pulses has been observed. Also, the long-time scale stability of the mean values of the probe current in both states was found to improve when applying the sinusoidal signal. The effect of the high frequency sinusoidal signal on the performance of the virtual memristor was attributed to the resonant activation of the oxygen ion migration via the oxygen vacancies by the alternating external electric field.

Ballistic Electron/Hole Emission Microscopy (BEEM/BHEM) has been applied to imaging and spectroscopy of Au nanoclusters (NCs) embedded into ultrathin (≈6 nm thick) yttria-stabilized zirconia (YSZ) films on Si substrates prepared using magnetron sputtering and annealing. Such structures are promising for resistive switching in non-volatile memory applications. According to the High Resolution Cross-sectional Transmission Electron Microscopy (HR X-TEM) data, the nearly spherical Au NCs of 1.5 to 3.5 nm in diameter were arranged almost in a single sheet between the YSZ layers. The BEEM images demonstrated the spots of increased collector current of 1 to 2.5 nm in size which are related to ballistic electron tunnelling via the Au NCs. The BEEM/BHEM spectra of the NCs demonstrated stepwise features attributed to the quantum confined states in the Au NCs. By using the best fit between the quantum confined energy states determined from the BEEM/BHEM spectra, the estimate of the NC diameter and the ones calculated for a spherical quantum dot yielded 1.7 to 3.3 nm which is consistent with the HR X-TEM data. The results of the present study demonstrate the capabilities of BEEM/BHEM in characterizing ultrathin dielectric films with metal NCs in research and also in industry.

Structural, optical and spectroscopic properties of Tm3+:Lu2O3 ceramics were studied. CW laser operation at 2068 nm with an output power of up to 34 W and a slope efficiency of 44% was obtained. Q-switched ocsilation with a pulse duration of 100-150 ns and a repetition rate of 1-10 kHz was achieved. Passive mode locking was achieved using an ion-implanted InGaAsSb quantum-well based SESAM or single graphene layer. Transform-limited pulses as short as 180 fs are generated at 2076 nm with an average output power of 400 mW and a pulse repetition frequency of 121.2 MHz. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The single sheet arrays of Au nanoparticles (NPs) embedded into the ZrO2(Y), HfO2(Y), and GeOx (x≈2) films have been fabricated by the alternating deposition of the nanometer-thick dielectric and metal films using Magnetron Sputtering followed by annealing. The structure and optical properties of the NP arrays have been studied, subject to the fabrication technology parameters. The possibility of fabricating dense single sheet Au NP arrays in the matrices listed above with controlled NP sizes (within 1 to 3 nm) and surface density has been demonstrated. A red shift of the plasmonic optical absorption peak in the optical transmission spectra of the nanocomposite films (in the wavelength band of 500 to 650 nm) has been observed. The effect was attributed to the excitation of the collective surface plasmon-polaritons in the dense Au NP arrays. The nanocomposite films fabricated in the present study can find various applications in nanoelectronics (e.g., single electronics, nonvolatile memory devices), integrated optics, and plasmonics.

It has been shown that the presence of silicon nanoparticles in a layer of porous silicon saturated with tungsten-tellurite glass causes an increase in the photoluminescence quantum efficiency of erbium (1530 nm) by an order of magnitude in the case of long-wavelength excitation and an enhancement of the ytterbium photoluminescence (980 nm) by almost 50 times and erbium photoluminescence by 25 times in the case of short-wavelength pumping. This luminescence enhancement is explained by the formation of additional channels of transfer of external excitation by silicon nanocrystallites in porous silicon to impurity ytterbium and erbium ions in tungsten-tellurite glass.

The structural, optical, and spectroscopic properties of new Tm 3+ : Lu2O3 laser ceramics are studied. The average size of a ceramic grain (crystallite) is found to be 540 - 560 nm. The absorp- tion spectrum measured in the near-IR region shows that this ceram- ics can be pumped by commercially available laser diodes at wave- lengths of 796 and 811 nm. The high-transmission region of the ceramics in the mid-IR region extends to 7 mm. Investigations of the luminescence spectrum in the region of 1.75 - 2.2 mm upon laser- diode pumping show strong lines peaked at wavelengths of 1942, 1965, and 2066 nm. Ellipsometric measurements yield refractive indices n » 1.92 at the pump wavelength 796 nm and n » 1.94 at the laser wavelength 2066 nm. Continuous-wave lasing of a Tm3+ : Lu2O3 ceramic laser at a wavelength of 2066 nm is demonstrated under diode-laser pumping at wavelengths of 796 and 811 nm.

Changes in the refractive indices of thin films of three polymeric organosilanes at wavelengths of 400-1500 nm, occurring under UV radiation, were examined.

It is shown that capacitors based on stabilized zirconia with gold nanoparticles exhibit nonlinear properties: the admittance of these capacitors depends on the amplitude of the control voltage, test-signal frequency, and temperature. The nonlinearity is due to electron capture by traps generated during nanoparticle formation. The possibility of determining the trap parameters by measuring the capacitor admittance has been established.

Bipolar resistive switching in metal-insulator-metal structures based on a double-layer insulator composed of a layer of yttria-stabilized zirconia (YSZ) containing 12 mol % Y2O3 and a layer of GeOx is studied. It is shown that the incorporation of an additional GeOx layer into the structure leads to a significant decrease in the variation of resistive switching parameters at both negative and positive voltages. Au/Zr/GeOx/YSZ/TiN structures exhibit a high stability of the resistance ratio in high-resistance and low-resistance states during cyclic switching. The studied structures can be used for designing next-generation nonvolatile memory elements.

Bipolar resistive switching in metal-insulator-semiconductor (MIS) capacitor-like structures with an inert Au top electrode and a Si3N4 insulator nanolayer (6 nm thick) has been observed. The effect of a highly doped n +-Si substrate and a SiO2 interlayer (2 nm) is revealed in the changes in the semiconductor space charge region and small-signal parameters of parallel and serial equivalent circuit models measured in the high- and low-resistive capacitor states, as well as under laser illumination. The increase in conductivity of the semiconductor capacitor plate significantly reduces the charging and discharging times of capacitor-like structures.

We report on the experimental observation of the effect of optical excitation on resistive switching in ultrathin ZrO2(Y) films with single-layered arrays of Au nanoparticles. The samples were prepared by depositing nanometer-thick Au films sandwiched between two ZrO2(Y) layers by magnetron sputtering followed by annealing. Resistive switching was studied by conductive atomic force microscopy by measuring cyclic current-voltage curves of a probe-to-sample contact. The contact area was illuminated by radiation of a semiconductor laser diode with the wavelength corresponding to the plasmon resonance in an Au nanoparticle array. The enhancement of the hysteresis in cyclic current-voltage curves due to bipolar resistive switching under illumination was observed. The effect was attributed to heating of Au nanoparticles due to plasmonic optical absorption and a plasmon resonance, which enhances internal photoemission of electrons from the Fermi level in Au nanoparticles into the conduction band of ZrO2(Y). Both factors promote resistive switching in a ZrO2(Y) matrix.

We have studied the photoluminescence (PL) of GeO2 and 90 mol % SiO2-10 mol % GeO2 films synthesized by method of RF magnetron sputtering and then irradiated with silicon ions and annealed. The PL of silicon-implanted GeO2 films, related to the presence of Si nanocrystals (nc-Si), was observed for the first time. It is established that the transformation of the defect centers responsible for the PL in the spectral range 350–600 nm, as well as the formation of nc-Si emitting in the region of 700–800 nm, significantly depend on the matrix type. In particular, the PL intensity at 700–800 nm in 90 mol % SiO2-10 mol % GeO2 films is weak. The role of the isovalent substitution of Si and Ge atoms in the transformation of defect centers and the formation of nc-Si is discussed.

The photoluminescence (PL) of Si + -implanted SiO 2 thermal films and ( 1 1 ¯ 0 2 ) sapphire substrates was studied for wide ranges of ion doses and annealing temperatures ( T ann ). The regularities of the PL at 780 nm from Si nanocrystals (NC) embedded in SiO 2 matrix for T ann = 1000 – 1200 ° C are described based on a model that takes into account coalescence of nearest NCs and dependence of radiative recombination rate on the NC size. Two PL bands found in Si + implanted Al 2 O 3 before and/or after annealing ( T ann = 500 – 1100 ° C ) are compared with those from Ar + -implanted samples and referred to the emission from Si NCs and defects.

We report on the experimental observation of the electrical oscillations in an oscillating loop connected to a contact of a conductive probe of an atomic force microscope to a tunnel-transparent (≈ 5 nm thick) SiO2/Si(001) film with embedded Au nanoparticles. The oscillations were attributed to the negative differential resistance of the probe-to-sample contact originating from the resonant electron tunnelling between the probe and the Si substrate via the quantum confined electron energy states in small (~1 nm in size) Au nanoparticles. This observation demonstrates the prospects to build an oscillator nanoelectronic device based on an individual nanometer-sized metal nanoparticle.

A method of connecting several p +-n junctions in the same Si:Er/Si structure is demonstrated; this method makes it possible to increase the electroluminescence intensity at a wavelength of 1.54 μm. The structures have been grown by sublimation molecular-beam epitaxy.

Si:Er layers in diode structures were doped with Al, Ga, or B during growth by sublimation molecular-beam epitaxy. As a result, a sharp increase in the electroluminescence intensity at a wavelength of 1.5 μm was observed in diodes with thick bases (as large as 0.8 μm).

Metal nanoclusters embedded into the ultrathin dielectric films attracted much attention in recent years due to their unusual electronic, optical, etc., properties differing from those of the bulk metals essentially and, hence, to the prospects of their applications in novel nanoelectronic, single electronic, non-volatile memory, etc., devices. Here, we report on the experimental observation of the electrical oscillations in an oscillating loop connected to a contact of a conductive probe of an Atomic Force Microscope to a tunnel-transparent ( ∼6.5 nm thick) yttria stabilized zirconia film with embedded Au nanoclusters on the Si substrate. The oscillations were attributed to the negative differential resistance of the probe-to-sample contact originating from the resonant electron tunnelling between the probe and the Si substrate via the quantum confined electron energy levels in small ( ≈2.5 nm in diameter) Au nanoclusters. This observation demonstrates the prospects of building an oscillator nanoelectron...