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The possibility of modifying the photoluminescence properties of porous silicon by irradiation with low doses of γ photons from a 226Ra radioisotope source and bremsstrahlung is demonstrated. The position of the longest photoluminescence wavelength tends to shift to the short-wavelength region of the spectrum. The emission efficiency increases upon irradiation of both the substrate and the layer formed.

A comparative study of the optical and morphological properties of different modifications of silicon and their dissolution upon interaction with distilled water and a biologically active medium is carried out. For the biologically active medium, nonpathogenic baker’s yeast (Saccharomycetes cereviseae) is chosen. It is shown that water and the biologically active medium interact with the surface of the materials and, thus, change the surface morphology and produce a modified layer. The strengths of the effect upon nanoparticles, nanoparticle-based structures (porous silicon), and single-crystal silicon doped with different types of impurities to different levels are different.

The photoelectric and photovoltaic properties of structures based on mesoporous silicon passivated with iron (SiMP:Fe) are studied. It is shown that these properties ambiguously depend on the iron concentration. In the case of a sample with space-charge-limited currents (SCLCs), the charge-transport mechanism in the Al-SiMP:Fe-p-Si-Al heterostructure changes under illumination from the SCLC type to the barrier type. Passivation with 0.1–0.2 at % iron stabilizes not only the electrical, but also the photoelectric and photovoltaic properties of the structures. A further increase in the Fe concentration gives rise to new traps caused by the appearance of iron and silicon oxides, which leads to instability of the properties. The structures exhibit high sensitivity under low-level illumination. The open-circuit voltage is 16 mV under AM-1 irradiation (∼2 mW/cm2).

The structure and elemental composition of graphite inclusions uncovered on high-strength cast iron by etching are studied. The chemical composition at various points and regions of graphite inclusions is determined. It is shown that the globular graphite is a unique lamellar-spiral system of micro- and nanoformations.

The current-voltage and capacitance-voltage characteristics of structures based on mesoporous silicon, obtained by electroless etching with passivation by iron, (SiMP:Fe) are investigated. It is shown that the conductivity and barriers in Al-SiMP:Fe-p-Si-Al heterostructures ambiguously depend on the Fe concentration. Passivation by iron changes not only the conductivity of the SiMP:Fe layer but also the character of carrier transport at low frequencies. At an iron concentration of ∼1 at % tunneling transport through barriers becomes dominant in comparison with jumps over dangling bonds. Passivation of the SiMP layer by iron stabilizes the SiMP electrical properties (which is confirmed by the values of the trap concentrations estimated from the current-voltage characteristic) of structures subjected to long-term storage. This is likely to be related to the interaction between iron ions and the silicon surface with the formation of oxides.

The electrical and photoelectric properties of nanostructures with porous silicon layers obtained by electroless etching of silicon have been investigated. It is found that the photoelectric and photovoltaic properties of these structures depend on their morphology and are determined by not only the properties of the modified layer, but also the presence of possible barriers in the layered porous silicon. The ratio of the photoconductivity to the dark conductivity reached 102−5 × 102. An open-circuit voltage V oc was detected that amounted to ∼250 mV at an incident light power close to AM-1 (∼100 mW/cm2). In this case, the density of short-circuit current I sc was about 20 μA/cm2.

The electron-transport processes in structures with oxidized porous silicon (OPS) are investigated during adsorption and desorption of polar molecules from atmosphere when the air pressure varies. It is shown that the cause of the existence of the open-circuit voltage in Pd-OPS-p+-Si-Al structures in the initial state is the surface-charge change on the Pd-OPS interface due to the polar-molecule adsorption from atmospheric air. The desorption of atmospheric-air molecules leads to a change in the current-voltage characteristics of structures, growth of the metal-OPS barrier in samples with the Schottky barrier, and initiation of current instabilities. The nanocrystalline nature of OPS manifests itself in the charge-carrier localization in quantum dots (QDs) during desorption in samples with space-charge-limited currents.

The effect of illumination and adsorption of polar molecules on the properties of structures based on oxidized porous silicon has been investigated. The specific features of these structures are fluctuations and a change in the sign of open-circuit voltage under the influence of long-term photoexcitation, time-related instabilities of the current in media with a high content of hydrogen sulfide, long periods of photocurrent decay after switching off the illumination, and the occurrence of negative photoconductivity in structures with space-charge-limited currents. The results obtained are explained by the presence of multiply charged traps of different types in oxidized porous silicon, their charge exchange, and the tunneling of charge carriers between silicon nanocrystallites.

A noncontact method for the express-testing of the relative deformation of lattice parameter (Δa/a ) of semiinsulating GaAs has been developed. This method is based on measuring the reflected radiation in band-to-band regions L3v - L1c and X5v - X3c. The suggested method ensures a resolution of 4 × 10-5 in determining (Δa/a ) and has a measurement accuracy of about 0.5%.

The effect of adsorption of hydrogen-sulfide and acetone polar molecules on current-voltage characteristics and time dependences of the current was studied for the 〈Pd-por-Si(O)-p+-Si-Al〉 structures based on oxidized porous silicon. Structures of two types were obtained—those with a Schottky barrier and those with space-charge-limited currents. The presence of a positive space charge was found near the palladium electrode; this charge defined the current-voltage characteristics in the region of V

In situ measurement of the formation process of low-dimensional porous silicon (PS) structures was developed. The measurements are based on the analysis of polyharmonic time dependence of the reflected radiation. The results show high sensitivity to H 2 S in PS based structures with catalytic (Pd, Ni) and ohmic (Al) electrodes. In the best samples the appearance of three molecules H 2 S on 10 9 molecules N 2 increased the electrical current value by a factor of 2–3. The structures selectively measure H 2 S concentration from 0.02 to 1000 ppm. It was found that unusually high reversible and nonreversible optical properties change because of the influence of gas solvents and alcohol. The exposure of PS layers to ethyalcohol vapor changes the color of PS from bright blue to crimson and the refraction coefficient in the IR region changes up to 0.06.

The kinetics of nitridization of a-Si:H layers, the properties of the structures that are formed and a-Si:H in them have been investigated. The changes occurring in the resistance of the a-Si:H layers in the course of nitridization are described in terms of the competition between doping, transport, and change in the thickness of the remaining a-Si:H layer. The experimental data on the band spectrum of superlattices with a-Si:H and a-SiNx:H layer thicknesses ∼35 A and ∼5 A, respectively, are in agreement with calculations in a model of interacting quantum wells with m*=(0.36±0.1)m0. Comparison of the properties of superlattices obtained by deposition of successive layers and nitridization of the a-Si:H layers showed that the latter can have a higher “structural perfection.”

The possibilities of creating sensors on the basis of silicon structures with classical and quantum-dimensional effects have been researched theoretically and experimentally. The technology of forming qnantuln-well and wire structures of porous and amorphous silicon and their modifications by multiparameter monitoring in situ has been studied. H 2 S sensor samples, developed on this basis, have a high sensitivity (on the level 10-20 ppb), low operating voltage (1-1.5 V), low power consumption (not more than 10 -8 -10 -6 W) and relative selectivity to hydrocarbons, CO and CO 2 . The most sensitive to H 2 S ate structures having p = 0.03 Ω cm, oxidized porous silicon layer thicknesses of 6-10 μcm, porosity of 0.75-0.8 and Pd layer thicknesses of 50-60 nm. The obtained results verify the principle possibilities in solving all growing contradictions between information processing and its reception by using low-dimensional structures.

The possibilities of micro- and nanoelectromechanical systems analogs of structures with PCMS have been researchers, theoretically. The offered structure is considered, in which the series switching of devices from one state in another is implemented and the self-distribution of the switched state along structure and its transition to a new state (principle of a domino) is carried out. On the base of the solution of differential equations linking cantilever bias (sag) to its design parameters and an affixed voltage it was established, that in meshes with d>100-150 nm to the defining speaker of meshes and processes of failure (the switching) are forces of Coulomb and elasticity, the Casimir force become essential at d

The semiclassical relationships for the complex refractive index are used to find the regions of integration of the Kramers-Kronig dispersion relation required to yield the spectral dependence of the optical properties of semiconducting materials in the vicinity of the plasma resonance of the charge carriers with a prescribed accuracy. The refractive index n and the absorption coefficientκ of heavily doped Si in the vicinity of the plasma resonance of the charge carriers are determined by the Kramers-Kronig method and by the method of two media. The values of n andκ obtained by these methods are in good agreement with values calculated on the basis of the Drude-Lorentz semiclassical theory of dispersion.

A nondestructive method of determining the parameters of epitaxial film systems is proposed based on a variational method of computing the coefficients of reflection and transmission of an electromagnetic wave in lamellarly inhomogeneous semiconductor structures. Structures of the type low-alloy film-transition layer-high-alloy substrate are considered with various prescriptions for varying the concentration of the alloying additives in the transition layer near the plasma resonance of the charge carriers in the substrate. Preliminary experimental investigations of the epitaxial N-N+ structures of silicon are in satisfactory agreement with computed data. The proposed method makes it possible to determine the thickness of the low-alloy layer and of the transition layer separately on the basis of the spectral dependence of the reflected radiation.