Photoelectrical properties of nanoporous silicon

The optimal composition of etchant solution and etching time for chemical treatment to obtain nanoporous Si have been determined. Influence of nanocrystal dimensions on the electrophysical and photoelectrical properties of heterojunctions has been studied. The current-voltage characteristics of nanoporous Si with various nanocrystal dimensions were measured. It was ascertained that lux-ampere characteristics have a linear range and sublinear one, which almost reaches the asymptote at the intensity of light above 10,000 lux. Nanoporous Si on the substrate of Si single-crystal has increased sensitivity to the humidity in comparison with that of metallurgical Si. The obtained results can be applied for development of highly sensitive sensors of humidit

Structural properties, photoelectric and photoluminescent characteristics of nanostructured silicon

. Nanostructured silicon layers (3–60 nm) have been formed upon substrates of monocrystalline silicon with a very large area (100 cm2 ), multicrystalline and metallurgical silicon by stain etching. We studied optical and structural properties of nanostructured silicon using scanning tunnel microscopy, scanning electron microscopy, Auger electron spectroscopy, secondary ion mass spectrometry, and photoluminescence methods. Results of studying the nanostructured Si properties obtained using the method of chemical processing have confirmed an opportunity to create this multifunctional material with stable characteristics. The authors have developed the sensor systems with use of nanostructured silicon as a sensitive layer, which properties depend on thickness of the obtained layer and are controlled by parameters of the respective technological process. Using the example of the photoluminescent sensor with the nanostructured Si layer, it has been shown that such a sensor can be successfully used to detect small concentrations of toxins (pesticides phosalone 10⁻⁸ - 10⁻⁹ mol/l ) as well as for specific biological pollutants, such as protein components, polysaccharides, cells worsening the quality of products of biotechnological synthesis

Structure and luminescence study of nanoporous silicon layers with high internal surface

In this work, the technique of formation of homogeneous nanoporous silicon layers with high internal surface on solar cell substrates by stain etching is developed. Emission and structure properties of such layers were studied by photoluminescence (PL), photoluminescence excitation, Auger electronic spectroscopy, atomic force microscopy and scanning tunnel microscopy methods. It was observed that nanoporous layers are of high homogeneity and their thickness is ~20-25 nm. It was shown that the higher PL intensity of such layers in comparison with PL intensity of the layers prepared on standard substrates in the same regimes is connected with the higher internal surface. The increase of PL intensity during prolonged aging in air at the room temperature was observed

Morphologic and optical characterization of ZnO:Co thin films grown by PLD

The morphological properties of the surface and optical characteristics of nanocomposite ZnO:Co structures grown on substrates of monocrystalline silicon and sapphire by pulsed laser deposition (PLD) method have been studied. The influence of thermal annealing on formation of characteristically developed surface of films has been analyzed. The experimental transmission and reflectance spectra in the visible region have been measured. In the framework of the dielectric function, the optical constants n and k and dispersion parameters of oscillators that provide the best fit with experimental data have been obtained. From the infrared reflectance spectra of ZnO:Co structures, the frequency positions of Е₁(LO) and Е₁(ТО) optical phonons have been determined. It gives a possibility to suppose that the obtained films possess the wurtzite structure

Study of nanostructured layers of single-crystal silicon by scanning tunnel spectroscopy

The nanostructured silicon surface has been studied using the scanning tunnel microscopy and spectroscopy in air. The local density of electron states was defined as normalized differential tunnel conductivity (dI/dU)(I/U). The surface morphology has been found to be characterized by the presence of a homogeneous nanostructure on the initial substrate microrelief. For the first time it has been shown that the spectrum of electron states changes considerably during the growth of a nanostructured silicon film