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The characteristics of metal-insulator-semiconductor (MIS) structures based on insulating PbSnTe:In films with compositions in the vicinity of band inversion grown by molecular-beam epitaxy (MBE) are studied. It is shown that a number of features of the films can be due to a ferroelectric phase transition with a Curie temperature in the range of about T ≈ 15–20 K.

The dependence of the photoconductivity sign on the bias voltage, intensity, and duration of illumination is studied for PbSnTe:In films in the space-charge-limited current regime. The role of traps (including surface ones) with a complex energy spectrum in the effects under observation is discussed.

Using Monte Carlo simulations, we studied the effect of readsorption on the growth rate and morphology of AIIIBVnanowires. It is demonstrated that readsorption of arsenic leads to an increase in the growth rate and premature consumption of a seed drop. The reabsorption of metal atoms leads to a slowdown in the axial growth but prolongs the growth, since it prevents the droplet from disappearing after the length of the nanowire reaches the diffusion length of the metal atoms along the side walls of the wire. It is demonstrated that it is possible to increase the diffusion length of group III elements along the side walls of the nanowire using the pulsed growth mode.

The initial stages of planar self-catalyzed GaAs nanowire growth via the vapor-liquid-solid mechanism are considered by a kinetic lattice Monte Carlo model. The shapes of the nanocrystals being formed under a catalyzed droplet are presented for three GaAs substrate orientations (111)A, (111)B, (001). The most stable planar GaAs nanowire growth was observed on GaAs(111)A substrates.

The main features of self-catalyzed III–V nanowire growth according to the vapor-liquid-solid mechanism were analyzed using Monte Carlo simulation. The nanowire growth kinetics, flux ratio influence on the nanowire morphology and growth rate were considered. For some growth conditions, the self-equalization effect of metal drop sizes during the self-catalyzed III–V nanowire growth was demonstrated. It is revealed that, only under the adsorption growth mode, all drop sizes reach a single stationary value.

The growth temperature dependences of the capacitance–voltage characteristics and chemical stability of the CaF2/BaF2 buffer layers formed on Si by molecular beam epitaxy have been investigated. Secondary ion mass spectrometry and X-ray photoelectron spectroscopy studies of the CaF2/Si interface suggest that the observed variations can be caused by the enrichment of the Si surface layer with calcium.

A kinetic lattice Monte Carlo model is used to study the Ga droplets self-propelled motion along GaAs(111)A and (111)B surfaces during the initial stage of high-temperature annealing. An estimation of the droplet velocity, running along (111)A and (111)B surfaces, in a wide temperature range, is carried out. The mechanism of small Ga drops movement during high-temperature annealing is suggested. Different directions of droplets motion and the morphology of drop-crystal interface on (111)A and (111)B substrates are determined by a difference in the etching rate of (111)A and (111)B facets by liquid gallium. It is shown that metal droplets can cause step bunching.

The process of GaAs and InAs substrates high-temperature annealing under the Langmuir evaporation conditions is studied by Monte Carlo simulation. The temperature range of gallium arsenide and indium arsenide congruent and incongruent evaporation are determined. It was demonstrated that the congruent evaporation temperature Tc is sensitive to the vicinal surface terrace width. The decrease of the terrace width results in a decrease in the congruent evaporation temperature. The Ga and In diffusion lengths along the (111)A and (111)B surfaces at congruent temperatures are estimated. The surface morphology transformation kinetic during high-temperature annealing is analyzed.

Based on the notions that PbSnTe:In is a direct-gap semiconductor, the radiative-recombination lifetime is calculated, and the photocurrent relaxation and dependences of the instantaneous electron and hole lifetime are calculated under the assumption that PbSnTe:In is a disordered structure containing capture centers. These calculations explain such experimentally observed peculiarities of PbSnTe:In as a high photosensitivity in a wide wavelength range, pinning of the Fermi level, and long-term photocurrent relaxation. Calculations are also compared with experimental data and the possible parameters of photodetectors are evaluated.

The nanostructures formation process using the droplet epitaxy technique was investigated by Monte Carlo simulation. The simulation was fulfilled for two-dimensional and three-dimensional geometry substrates. The nanostructures morphology dependence on the growth temperature was presented. Crystal clusters, single and double rings were observed. The nanostructures shape was shown to be determined by the gallium diffusion length. The conditions of double rings formation during the droplet epitaxy were considered using analytical and numerical approaches. The factors that determine the rings location and shape were analyzed. The growth morphology was demonstrated to be dependent on the initial distance L between the droplets. The double ring formation was possible at a low droplet density only, when the As-stabilized region could be created between the droplets.

Results are presented from experimental and theoretical studies of the dependence of the rate of quantum key distribution on the average number of photons in a laser pulse. The experimental data are obtained using atmospheric and fiberoptic experimental setups for a quantum key distribution based on the BB84 protocol.

A brief overview of the current state of the experimental research on the development of the element base of quantum computers with qubits based on single neutral atoms trapped in optical traps. The requirements for qubits, peculiarities of single neutral atoms as qubits, methods for the quantum register development and for the implementation of single-qubit quantum logic operations in the laser and microwave fields, and two-qubit operations through the dipole–dipole interaction after a short laser excitation of atoms to the Rydberg states are discussed. The results of the experiments on the observation of the interaction of two Rydberg atoms at a Forster resonance controlled by the dc and radio-frequency electric field are presented.

Quantum cryptography can provide almost complete security of the data transmitted in optical telecommunication systems by single photons based on the laws of quantum mechanics. The paper presents a brief overview of the element base and experimental investigations in the field of quantum cryptography and data transmission by single photons in atmospheric and optical fiber quantum communication lines. Two experimental setups for the single-photon quantum key distribution in the atmospheric and optical fiber quantum channels are described. The results of the quantum key distribution experiments performed on them are given.

The phase and elemental compositions of GeSi heterostructures deposited on non-refractory substrates are analyzed by using a non-destructive express technique, i.e., the Raman spectroscopy. It is shown that application of pulsed laser annealing allows one to vary the elemental composition and size of nanocrystals formed from solid alloys of germanium and silicon.

Experiments and simulations are performed to study the formation of silicon nanocrystals (Si-NCs) in multilayer structures with alternating ultrathin layers of SiO2 and amorphous hydrogenized silicon (α-Si:H) during high-temperature annealing. The effect of annealing on the transformation of the structure of the α-Si:H layers is studied by methods of high-resolution transmission electron microscopy, Raman spectroscopy, and photoluminescence spectroscopy. The conditions and kinetics of Si-NC formation are analyzed by the Monte Carlo technique. The type of the resultant crystalline silicon clusters is found to depend on the thickness and porosity of the original amorphous silicon layer located between SiO2 layers. It is shown that an increase in the thickness of the α-Si layer in the case of low porosity leads to the formation of a percolation silicon cluster instead of individual Si nanocrystals.

The design and characteristics of a three-spectrum multielement photodetector device with a sensitivity range from 0.6 to 12.0 μm, which consists of three arrays of photodetectors having sensitivity ranges 0.6–0.9, 3–5, and 8–12 μm, are described. Methods of fabrication of photodetector arrays, the photodetector device as a whole, and its photoelectric characteristics are presented.

This paper presents a brief review of experimental studies in quantum cryptography and quantum key distribution by single photons in atmospheric and fiber-optic quantum communication channels. Two experimental setups for quantum key distribution developed at the Rzhanov Institute of Semiconductor Physics SB RAS are described. The dependence of the quantum key distribution rate on the average number of photons μ in the laser pulse was studied. For μ > 0.3, there is a discrepancy between theory and experiment. The reasons for this are, first, the nonzero probability of multiphoton pulses occurring in quantum transmission and counted as single photons by single-photon detectors and, second, the rejection of the cases where several single-photon detectors click simultaneously in quantum key sifting because the measurement result is not determined in these cases.

A Monte Carlo lattice model is proposed to describe the formation of semiconductor nanostructures by the vapor–liquid–solid growth mechanism. This model is used to simulate the growth of GaAs nanostructures by the droplet epitaxy technique in the temperature range from 500 to 600 K in As2 fluxes with intensity of 0.005–0.04 ML/s. The morphology of the formed structures is demonstrated to depend on the growth parameters. Etching of the GaAs substrate by a gallium droplet is studied. The ranges of temperature and As flux rates necessary for the formation of GaAs nanorings are determined. The conditions of the formation of single and double concentric rings are analyzed.

The possibility of improving the performance of semiconductor integrated circuits by replacing the silicon layer in metal–insulator–semiconductor (MIS) transistors by a material with higher charge-carrier mobility. It is shown that germanium is best suited for this purpose based on its properties. Developments made in this area in different laboratories both in Russia and abroad are discussed.

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

A kinetic Monte Carlo model of droplet epitaxy is suggested and realized. A basis for the Monte Carlo model is the vapor–liquid–solid mechanism. The proposed model was used for the analysis of GaAs nanostructure formation mechanism during crystallization of Ga drops under the arsenic flux. The dependences of the grown structure morphology on temperature, As 2 flux intensity and GaAs substrate surface orientation were analyzed. Depending on temperature and arsenic flux intensity, different shapes of nanostructures (crystal dots, core–shell compact clusters, nanoholes and nanorings) were achieved. A lack of etching of GaAs substrates with (1 1 1)А and (1 1 1)В surface orientations by liquid gallium was revealed. Nanohole and nanoring formation was observed only on substrates with (0 0 1) surface orientation. The kinetics of nanoring formation was examined.

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.

Silicon-nanocluster formation upon the annealing of SiOx (1 ≤ x < 2) layers is studied with the use of the lattice Monte Carlo model. The simulation is performed taking into account an additional mechanism of silicon transport due to the diffusion of silicon-monoxide (SiO) particles. It is demonstrated that the presence of SiO in the system leads to the growth of a critical silicon-nanocluster nucleus and can increase the nanocluster growth rate. Silicon-nanocluster formation upon the annealing of SiOx layers occurs only for the composition with x < 1.8. Upon the annealing of SiOx layers on a silicon substrate, a region depleted of silicon nanoclusters is observed in the layer adjacent to the substrate, which allows the formation of silicon nanoclusters in the SiO2 matrix at a certain distance from the Si/SiO2 interface.

A kinetic Monte Carlo model of silicon nanocluster (Si-nc) formation during high temperature annealing of Si suboxide layers was suggested. The model takes into account, along with silicon and oxygen atom diffusion, the processes of silicon monoxide creation and dissociation. It was demonstrated that the presence of SiO in the system results in an increase of Si-nc critical nuclear size and can accelerate nanocluster growth. It was found that Si-ncs were formed only in the SiO x layer with x 2 film containing nonstoichiometric SiO x layers resulted in Si-nc or cavity formation depending on temperature. The type of the process was determined by ratio between SiO dissociation and evaporation rates.

This article is devoted to the current state of experimental studies on the use of single neutral atoms caught by optical traps as quantum computer qubits and on the use of single photons for information transfer. The experimental results of observing interaction between two Rydberg atoms are presented, and experiments in quantum cryptography and data transfer by single photons are considered.

The flowing of the injection current in Pb1 − xSnxTe:In structures (x ≥ 0.3) with various metal contacts at the temperature of helium is considered. The current-voltage characteristics (CVCs) of the structures in the dark and when they are illuminated from the blackbody model are given. It is found that the CVCs depend on the materials of the metal contact. The localized state density distribution over the forbidden band in structures with various contacts is given and the influence of the contact region and localized states on the CVC is discussed. The problems of constructing photodetectors with optimum threshold characteristics are discussed.

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.

The process of axial and radial Si–Ge heterostructure formation during nanowire growth by vapor–liquid–solid (VLS) mechanism was studied using Monte Carlo (MC) simulation. It was demonstrated that radial growth can be stimulated by adding chemical species that decrease the activation energy of precursor dissociation or the solubility of semiconductor material in catalyst drop. Reducing the Si adatom diffusion length also leads to Si shell formation around the Ge core. The influence of growth conditions on the composition and abruptness of axial Ge–Si heterostructures was analyzed. The composition of the Ge x Si1–x axial heterojunction (HJ) was found to be dependent on the flux ratio, the duration of Si and Ge deposition, and the catalyst drop diameter. Maximal Ge concentration in the HJ is dependent on Ge deposition time owing to gradual changing of catalyst drop composition after switching Ge and Si fluxes. The dependence of junction abruptness on the nanowire diameter was revealed: in the adsorption-induced growth mode, the abruptness decreased with diameter, and in the diffusion-induced mode it increased. This implies that abrupt Ge–Si HJ in nanowires with small diameter can be obtained only in the chemical vapor deposition (CVD) process with negligible diffusion component of growth.

The process of formation of Si-Ge heterostructures based on nanowhiskers (NWs) grown according to the vapor-liquid-solid mechanism is studied using the Monte Carlo simulation. It is found that, during growth of axial heterojunctions (HJs), it is impossible to obtain an atomically flat Si-Ge HJ, which is related to a gradual change in the catalyst-drop composition during the switch between fluxes. The dependence of the composition of the GexSi1 − x transition layer on the ratio of fluxes and on the Ge and Si deposition time is studied. It is found that the width of the axial Si-Ge HJs depends on the NW diameter. It depends linearly on the diameter under the adsorption-induced growth conditions and decreases with increasing diameter under the diffusion-induced growth conditions. This means that, as the NW thickness decreases, abrupt HJs in the Ge-Si system can be obtained only in the case of chemical-vapor-deposition growth in which the diffusion-induced growth component is insignificant.

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.

The kinetic Monte Carlo (MC) model of nanowhisker (NW) growth is suggested. Two variants of growth are possible in the model—molecular beam epitaxy (MBE) and chemical vapor deposition (CVD). The effect of deposition conditions and growth regimes on the whisker morphology was examined within the framework of the vapor–liquid–solid (VLS) mechanism. A range of model growth conditions corresponding to NW and nanotube formation was determined. The suggested MC model was used for analyses of the morphology of the catalyst–whisker interface and for examination of Si–Ge whisker growth.

The growth of silicon nanowhiskers on the Si (111) surface activated with Au is studied by Monte Carlo simulation. The dependences of the rate of growth of whiskers on the temperature, deposition rate, and catalyst droplet diameter are obtained, and the morphological properties of the growing wirelike nanocrystal are studied. In addition to the growth of nanowhiskers, a number of experimentally observed effects, such as migration of the droplet from the whisker top, faceting of the whisker sidewalls, and branching are established for the model system. It is shown that, under certain conditions of wetting of the whisker material with the catalyst, formation of hollow nanowhiskers is possible.

The Monte Carlo method is used to simulate the kinetics of growth and the morphology of one-component nanowhiskers. It is demonstrated that for a proper choice of catalyst and substrate materials, hollow nanowhiskers can grow. The nanotube growth conditions are established. In the process of vapor-liquid-crystal crystallization, the dependence of the activation energy of chemical reactions on the neighboring species and their number in the first coordination sphere of reagent atoms is considered.

The process of nanowhisker formation on the substrates activated by catalyst drops was investigated by Monte Carlo simulation. Influence of deposition conditions on whisker morphology was considered. Straight whiskers with uniform diameter could be grown using catalyst possessing large contact angle with whisker material. It was demonstrated that variation of growth conditions in such physicochemical system may result in nanotube formation. Atomic mechanism of hollow whisker formation was suggested. The range of model growth conditions for nanowhisker and nanotube formation were identified.

Nanowhisker formation on substrates activated by catalyst drops is studied by Monte Carlo simulation. Dependences of the whisker growth rate on diameter are investigated for various growth modes. The influence of deposition conditions on whisker morphology is examined. It is shown that straight thin whiskers of uniform thickness can be obtained only using a catalyst having a large contact angle with the whisker material. In such a physicochemical system, variation of growth conditions can result in nanotube formation. An atomic mechanism for the formation of a hollow whisker is proposed. Ranges of model growth conditions suitable for the growth of nanowhiskers and nanotubes are determined.

This paper gives experimental results of quantum key distribution on a fiber-optic setup at a telecom wavelength of 1555 nm. A self-compensated two-channel optical circuit is used. Quantum key distribution was performed by coding the phase states of single photons radiated by a pulsed semiconductor laser in two alternative nonorthogonal bases. Specially developed single photon counters based on InGaAs: InP avalanche photodiodes were employed as high-sensitivity photodetectors. The results of investigation of the quantum efficiency, probability of afterpulses, and noise level for various operating modes of the detectors at temperatures from −40 to −60°C are given. A key distribution rate of 450 bit/s was obtained for a single-mode fiber-optic quantum communication channel between the receiver and sender 25 km long at a laser pulse clock frequency of 5 MHz and an average number of photons per pulse of about 0.2. For the achieved photodetector characteristics, the average number of errors in the quantum key did not exceed 3.7%.

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

We report for the first time on the creation of 288 × 2 matrix photodetectors with an element size of 25 × 25 μm based on PbSnTe:In/BaF2/CaF2/Si structures and present their threshold characteristics. The detection ability of about 90% elements ranges from 7.2 × 1012 to 8.7 × 1012 cm Hz0.5/W at T = 21.2 K. The proposed technology opens ways to the creation of monolithic matrix photodetectors operating in the far-IR range.

In this work, the lattice kinetic Monte Carlo model has been used to investigate morphological transformations in porous films of different density in the process of high-temperature annealing. The characteristics of porous films of different initial densities have been compared at different time moments of the sintering process. Layers with a porosity from 20% to 50% having a cubic lattice have been studied. It is shown that closed pores are formed in the film if the porosity is less than 25%; in films with a larger porosity, percolation pores arise. It has been established that the rate of sintering depends on the annealing time nonmonotonically.

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.

A variant of electron-spin quantum computer is discussed in which a film of high dielectric constant is used to provide interaction between qubits situated in silicon. Requirements to be satisfied by such a structure and possible ways of its fabrication are examined in the case of an In-doped Pb1−x SnxTe film.

A hypothesis of perpendicular dimer row formation along three-bilayer (3 BL) step was suggested. The hypothesis, explains the stability of 3 BL steps on the vicinal Si(1 1 1) surface deflected in 〈 1 ¯ 1 ¯ 2 〉 direction as well as the limitation of Ge and Si island height by 3 BL at the initial nucleation stages on Si(1 1 1) surface. The detailed examinations of STM images of 3 BL steps were carried out. New peculiarities of atomic structure of 3 BL single step on Si(1 1 1) and 3 BL steps on Si(5 5 7) surfaces were revealed. The results of STM images examination verify the hypothesis of perpendicular dimer row formation along the boundary of the 3 BL step.

Speeding up of step density oscillations (SDO) damping on singular surface with Schwoebel barriers was demonstrated by Monte Carlo simulation. Estimation of Schwoebel barrier necessary for complete absence of SDO was carried out. Increase of atomic surface anisotropy was shown to be responsible for slowing down SDO damping and oscillations phase shift for anisotropy similar to anisotropy on (0 0 1) reconstructed surfaces.

Using kinetic MC model simulation of ALD process is carried out. Influence of surface substrate relief and sticking center concentration on growth rate of ALD films at initial stages of growth are investigated. Relationship between growth rate and nucleus center concentration in a nonlinear regime is obtained. For increasing nucleation rate of ALD process combination of CVD and ALD processes in the first cycle is suggested. To increase ALD layers quality and reduce a nonlinear growth regime formation of loose rough surface layer on the substrate before deposition process is recommended.

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.

Pioneering experiments on single-photon quantum cryptography that are performed with a tailored setup are reported. The key is transferred by pulsed semiconductor lasers, which encode the polarization state of the photons in two mutually nonorthogonal bases. Photon detectors are based on C30902S silicon avalanche photodiodes. For a laser pulse repetition rate of 100 kHz and a mean number of photons per pulse of about 0.2, the key generation rate reaches ≈4 kbit/s. The error rate in the key does not exceed 1%.

A Monte Carlo simulation is reported of (i) the homoepitaxial growth of a continuous film on porous Si(111) and Si(001) surfaces and (ii) high-temperature annealing of a porous-silicon substrate. The simulation is based on a 3D model for diamond-type crystals. It is shown that homoepitaxy produces a smooth film on a (111) surface, whereas the film on a (001) surface shows {111} tetrahedral pits. It is found that the minimum deposited dose required for pore sealing is much lower for a (111) surface; this is true of all temperatures, deposition rates, and porosities considered. The difference in surface morphology between the two films is attributed to the influence of surface orientation on adatom migration. The variation is examined of pore penetration depth with respect to epitaxy conditions and porosity. Structural changes under annealing are investigated in the Si(001) case.