Phase-locked loop system based on the digital filter with adapted parameters

The phase-locked loop system based on a controlled phase detector??a digital filter with adapted parameters??has been proposed. The algorithm for adapting filter parameters has been developed. The statistical characteristics of operation of the system are investigated under the action of an additive white Gaussian noise. The proposed system is compared with traditional analogs and the Costas circuit.     

Electroluminescence at a wavelength of 1.5 μm in Si:Er/Si diode structures doped with Al,Ga, and B acceptors

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).     

Photoluminescence of GeSi/Si nanoclusters formed by sublimation molecular-beam epitaxy in GeH4 medium

The morphology and photoluminescence spectra of GeSi/Si(001) heterostructures with nanoclusters formed by sublimation molecular-beam epitaxy in GeH₄ medium are investigated as functions of growth conditions. It is established that the clusters nucleate by the Stranski-Krastanow mechanism; however, the coalescence processes substantially affect their morphology during further growth. Doubling of photoluminescence lines in nanoclusters associated with the radiative recombination inside the clusters and the blue shift of lines with increasing growth time associated with the Si diffusion from substrate into the clusters are observed. The conditions of forming uniform nanocluster arrays emitting at room temperature are determined.     

Automatic Control of the Freight Train Makeup

Construction of the stochastic models of routing the railway freight cars descending from the yard hump was considered. The models enable automatic control of railway train makeup.     

Electroluminescence at a wavelength of 1.54 μm in Si:Er/Si structures consisting of a number of <Emphasis Type="Italic">p-n</Emphasis> junctions

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.     

On the nature of electroluminescence at 1.5 μm in the breakdown mode of reverse-biased Er-doped silicon <Emphasis Type="Italic">p-n</Emphasis>-junction structures grown by sublimation molecular beam epitaxy

Electroluminescence features in the wavelength range of 0.9–1.65 μm were experimentally studied in the breakdown mode of reverse biased Si/Si:Er/Si p-n-junction structures grown by sublimation molecular-beam epitaxy. Based on the results of this study, a new physical model is proposed, in which radiative transitions in the near-infrared region are excited by recombination of electrons arriving at corresponding energy levels in the Si:Er layer due to their tunneling from the valence band of the p ⁺-layer in the electric field of the reverse biased p-n-junction. The model proposed is in qualitative agreement with main available experimental results.     

Electron spin resonance and photoluminescence in pyrolytic silicon nitride films irradiated with argon and molecular ions

The photoluminescence and electron spin resonance phenomena are studied at room temperature for pyrolytic silicon nitride films irradiated with argon ions or molecular nitrogen ions and annealed at temperatures in the range 500–1100°C. The absorption spectrum suggests that the broad photoluminescence band at 400–600 nm is due to electron transitions between the band tails. The low-dose irradiation with argon ions slightly reduces the photoluminescence intensity, whereas the high-dose irradiation followed by annealing at 800–900°C can induce a more than twofold increase in the intensity. At the same time, irradiation with nitrogen ions profoundly suppresses the integrated photoluminescence intensity that decreases by more than an order of magnitude. A correlation between the changes in the photoluminescence intensity and the amplitude of the ESR spectra on annealing of the silicon nitride films is observed.     

Photoluminescence of self-forming nanoclusters grown in GeSi/Si heterostructures by sublimating molecular beam epitaxy in GeH<Subscript>4</Subscript> medium

Morphology and photoluminescence spectra of GeSi/Si(001) with self-forming nanoclusters obtained by the sublimation molecular-beam epitaxy in GeH₄ medium under various process conditions are studied. It is found that the clusters are formed by the Stransky-Krastanov growth followed by the important coalescence processes. Doubling of the photoluminescence lines from the nanoclusters is caused by the radiative recombination; the progressing blueshift of the lines, by the Si diffusion from the substrate into the clusters. The conditions ensuring the growth of uniform nanocluster arrays exhibiting photoluminescence at room temperature are determined.     

Dependence of the concentration of ionized donors on epitaxy temperature for Si:Er/Si layers grown by sublimation molecular-beam epitaxy

The dependence of the concentrations of the Er impurity and ionized donors on the epitaxy temperature has been studied before and after annealing of Si:Er/Si layers grown by sublimation molecular-beam epitaxy. n-Si:Er layers have been grown in the temperature range 400–800°C and annealed in hydrogen atmosphere at a temperature of 800°C for 30 min. The possible nature of the donor centers is discussed.