Clusters of point and extended defects, arising in semiconductors as a result of radiation exposure, allow structures to acquire various properties that can be used in the manufacture of new generation devices for nanoelectronics. Numerical simulation of semiconductor materials used to research such processes is a resource-intensive and multifaceted task. To solve it, the multiscale modeling complex was created and the multiscale composition containing instances of basic composition models was set. An algorithm was developed that allows speeding up calculations for systems of large dimensions and accounting for a large number of interacting atoms. The structure of silicon with a complex of point defects was considered as a model. Molecular dynamics simulation was performed using the multiparameter potential of Tersoff. For the calculations, an effective approach to the implementation of parallel computing was presented, and software for parallelizing the computations was used, placed on the hybrid high-performance computing complex of the FRC «Computer Science and Control» of Russian Academy of Science. To implement the parallelized algorithm, the OpenMP standard was used. This approach has significantly reduced the computational complexity of the calculations.

It was shown that the developed high-performance software can significantly accelerate molecular dynamics calculations, such as the calculation of divacancy communication energy, due to the parallelization algorithm.

In this work, the influence of zirconium substitution in cubic spinel nanocrystalline CoFe₂O₄ on the structural, morphological and dielectric properties are reported. Zirconium substituted cobalt ferrite Co_1-xZr_xFe₂O₄ (x = 0.7) nanoparticles were synthesized by sol-gel route. The structural and morphological investigations using powder X-ray diffraction and high resolution scanning electron microscope (HRSEM) analysis are reported. Scherrer plot, Williamson–Hall analysis and Size-strain plot method were used to calculate the crystallite size and lattice strain of the samples. High purity chemical composition of the sample was confirmed by energy dispersive X-ray analysis. The atoms vibration modes of as synthesized nanoparticles were recorded using Fourier transform infrared (FTIR) spectrometer in the range of 4000–400 cm^-1. The temperature-dependent dielectric properties of zirconium substituted cobalt ferrite nanoparticles were also carried out. Relative dielectric permittivity, loss tangent and AC conductivity were measured in the frequency range 50 Hz to 5 MHz at temperatures between 323 and 473 K. The dielectric constant and dielectric loss values of the sample decreased with increasing in the frequency of the applied signal.

The Zn_1-xNi_xO nanoparticles have been synthesized by novel co-precipitation method and systematically characterized by XRD, SEM, TEM and photo luminescence. The XRD patterns confirm the hexagonal wurzite structure without secondary phases in Ni substituted ZnO samples. SEM and TEM are used for the estimation of particle shape and size. In PL study there is a peak in the range of 380—390 nm in all samples that is attributed to the oxygen vacancies. Gas sensing tests reveal that Ni doped ZnO sensor has remarkably enhanced performance compared to pure ZnO detected at an optimum temperature 100 °C. It could detect ethanol gas in a wide concentration range with very high response, fast response–recovery time, good selectivity and stable repeatability. The possible sensing mechanism is discussed. The high response of ZnO Nanoparticles was attributed to large contacting surface area for electrons, oxygen, target gas molecule, and abundant channels for gas diffusion. The superior sensing features indicate the present Ni doped ZnO as a promising nanomaterial for gas sensors. The response time and recovery time of undoped is 75 s and 60 s and 0.25 at.% Ni are found to be 60 s and 45 s at 100 °C respectively.

In the study of electron transport in low-dimensional structures, semiconductor heterostructures with a two-dimensional electron gas are often used. The conductive channel of these structures is separated from the gates by insulating regions, which can be formed in a varitey of ways. The peculiarities of such structures are the high quality of the initial plates and the need to change the topology in the research process. This makes the use of photolithography ineffective.
This paper discusses the technology of forming insulating grooves using an atomic force microscope — a method of pulsed force nanolithography, which allows both working with individual samples and forming narrow and deep grooves on the semiconductor that provide good insulating characteristics. The measured transport characteristics of the nanostructures created by this method confirm the presence of quantization of the channel conductivity and the absence of a noticeable number of introduced defects.

The effects of changing the acceptors concentration on the electrical characteristics of Au/Ti on Be-doped Al_0.29Ga_0.71As Schottky contact have been investigated in the temperature range of 100—400 K. Using three devices with three different doping levels, the barrier height (Φ_B), ideality factor (n) and series resistance (R_S) for each diode were evaluated using both thermionic emission (TE) theory and Cheung's method. Our experimental results showed that the sample with a moderate doping concentration of 3 · 10¹⁶ cm^-3 has the best performance, including ideality factor of 1.25 and rectification ratio of 2.24 · 10³ at room temperature. All samples showed an abnormal behavior of reducing Φ_B and increasing n with increase of temperature. This behavior was attributed, in case of low concentration samples, to barrier inhomogeneity and was explained by assuming a Gaussian distribution of barrier heights at the interface. While for the heavily doped sample, such non-ideal manner was ascribed with tunneling through the field emission (FE) mechanism.

In the present study, iron doped zinc oxide (ZnO : Fe) thin films were prepared by using a simple chemical spray pyrolysis technique by varying the doping concentration in the range, 0–6 at.% at a constant substrate temperature of 400 °C.The effect of Fe-doping concentration on the physical behavior of ZnO thin films were analyzed and discussed. The X-ray diffraction (XRD) patterns exhibited hexagonal wurtzite crystal structure without any secondary phases for all the films irrespective of the doping concentration. However, the preferential orientation changed from (002) to (101) plane with increase of Fe-doping. The Raman spectroscopy studies showed the peaks at 338 cm^-1, 438 cm^-1 and 574 cm^-1 which are the characteristic vibrational modes of ZnO. The scanning electron microscopic (SEM) images showed irregular shaped grains grown over the substrate surface. The X-ray photoelectron spectroscopy (XPS) studies confirmed the presence of Fe in 3+ state in ZnO layers. The Fourier transform infrared (FTIR) spectroscopy data revealed the presence of iron in the doped ZnO films by showing the modes related to iron in addition to ZnO. The optical properties revealed that the films with lower Fe-doping concentration (≤ 2 at.%) showed high transmittance and wide band gap than the pure and highly Fe-doped ZnO films. The evaluated band gap showed a red shift upon doping with the energy band gap decreased from 3.24 eV to 3.01 eV for the investigated doping concentration range. The photoluminescence spectra also showed similar optical behavior with quenching of PL signal intensity of the films. Moreover, all the Fe-doped ZnO films showed ferromagnetic behavior at room temperature.