I. G. Neizvestny

3D-model of epitaxial growth on porous {111} and {100} Si surfaces

A 3D Monte Carlo model of epitaxial and annealing processes on (111) and (100) surfaces of diamond-like crystals was developed. Simulations of epitaxial growth on porous Si(111) and Si(100) surfaces using this model were carried out. Distinct relief is formed over sealing pores due to diffusion differences on these surfaces. A smooth solid layer is formed on the (111) surface whereas pyramidal pits faceted by (111) planes are created over pores on the (100) surface. The deposited dose necessary for pore sealing is one order of magnitude greater on the Si(100) than on the Si(111) surface.

Experimental studies in quantum cryptography

A short survey on experimental works in quantum cryptography is presented. We describe experimental setups that were designed in the Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, for quantum key distribution through an air space and along a fiber-optic communication line. The results of the study of quantum efficiency parameters, probability of afterpulse appearance, and noise levels for different operation modes of InGaAs-InP avalanche photodiodes are presented.

Interlayer atomic diffusion as the reason for self-assembled quantum dot formation

Abstract Self-assembled 3D-islands formation during epitaxial growth was investigated using a kinetic Monte Carlo model. Schwoebel barriers for the explanation of 3D growth kinetics were suggested. The diffusion hop probability ratio for atom hops up to hops down χ , leading to 2D, 3D and Stranski–Krastanov growth modes, was obtained. The necessity of atomic flow from the island edge to the upper layers for 3D-island formation was demonstrated. Island size equalization during the growth process was observed for certain χ values. The new layer nucleus on the top of the island becomes the trap for atoms detached from the edges of the lower layer. Atomic flow to the upper layer increases and that is the reason for the equalization of separate 3D-island lateral sizes.

Semiconductor nanowire sensors

This article provides a description of the physical principles, design, and parameters of specific devices for chemical- and bio-sensing based on the change in the conduction of semiconductor nanowires caused by the surface charge of the studied object. Data concerning the sensitivity and selectivity of both single and matrix sensors are provided. This review also provides a description of biosensor autonomous power supply devices that use the energy of motion of a living organism

Quantum cryptography and quantum-key distribution with single photons

A brief overview of the current status of quantum cryptography is given. The results are presented of our preliminary experiments with free-space quantum-key distribution by means of single linearly polarized photons with coded polarization states according to the BB84 protocol, for which purpose a quantum-cryptography communication system is designed. Single photons are detected with a 50% probability using specially designed high-speed photodetectors based on silicon avalanche photodiodes, operated in Geiger mode with active avalanche quenching. A key generation rate of 3.8 kbit/s is obtained, the mean photon number per pulse being 0.2.

Industrial prospects of Pb1 − xSnxTe:In with x > 0.3 solid solutions for photodetectors with extended sensitivity spectral range

Photoelectric properties of Pb1 − xSnxTe:In films with composition x > 0.3 in the temperature range from 4.2 to 80 K have been investigated. High sample sensitivity to black-body radiation has been discovered at the temperature of helium, and as the temperature of the radiation source decreases the sensitivity increases, which can be connected with the optical-frequency transition in the short-wavelength infrared and terahertz spectral range. The detectivity value D* = 8.2 × 1016 cm · Hz1/2/W corresponding to the NEP = 3.1 × 10−18 W/Hz1/2, has been obtained at detector temperature 4.2 K and TBBR = 15 K.

Monte Carlo Simulation of Porous Layers Sintering

Kinetics of porous layer evolution during high-temperature annealing was investigated by Monte Carlo simulation. Sintering process of spongy one-component films with randomly distributed pores was studied. Layers with porosity from 20% to 50% with simple cubic and diamond-like lattices were under examination. Sintering rate was demonstrated to be non-monotone in time for any film porosity and different lattice coordination number. Metastable states of the system, dependent on time and temperature of annealing process, were revealed. Estimation of annealing time necessary to reach the definite sintering level under changes of annealing temperature was suggested.

Specific temperature-related features of photoconductivity relaxation in PbSnTe:In films under interband excitation

The time dependences of variations in the photoconductivity of PbSnTe:In films in the range of T ≈ 19—25 K upon interband excitation are studied. It is found that the character of conductivity relaxation after switch-off of illumination depends on the duration and intensity of the preceding illumination. In this case, the characteristic times of relaxation for various modes of illumination can differ by more than an order of magnitude. The obtained results are discussed in the context of a model assuming the presence of a quasicontinuous spectrum of capture levels in the band gap of PbSnTe:In and also a possible effect on the parameters of these levels of the ferroelectric phase transition, the temperature of which is found to be in the temperature range under study

Simulated growth of GaAs nanowires: Catalytic and self-catalyzed growth

The kinetic lattice Monte Carlo model of GaAs nanowire growth by the vapor-liquid-crystal mechanism is suggested. The catalytic and self-catalyzed growth of nanowires on the GaAs (111)B surface is simulated. The dependence of the morphology of the growing nanowires on the growth parameters is demonstrated. Upon self-catalyzed growth with gallium drops serving as the growth catalyst, the growth rate of the nanowires linearly depends on the arsenic flow in a wide range of arsenic flow rates. The decreasing dependence of the self-catalyzed growth rate of the nanowires on the initial gallium drop diameter is less steep, and the optimal growth temperature is higher than that for catalytic growth. It is shown that self-catalyzed growth is more sensitive to the ratio between the gallium and arsenic flow rates than catalytic growth.

Causes of the stability of three-bilayer islands and steps on a Si (111) surface

AbstractThe initial stages of growth of Ge and Si layers on a singular Si (111) surface result in an unusual morphology of the growth surface if the layers are deposited at a low rate; i.e., triangular islands with a height of as much as three atomic layers are formed. A simulation based on the Monte Carlo method has been used to show that an additional barrier with a height of 0.5–0.6 eV, serving to incorporate atoms into dimerized bonds at the edges of the triangular islands, brings about enhanced growth of the islands in relation to their height and a change in the triangles’ orientation. According to the suggested hypothesis, the increase in the islands’ height and the limitation of their height to three bilayers are due to the effect of the edge dimers, whose orientation changes when the height of a step perpendicular to the n