Silicon Crystals Research Articles

Stress analysis and dislocation cluster generation in silicon crystal with artificial grain boundaries

We conducted a dislocation and stress analysis on various grain boundaries (GBs) using silicon ingots that contained artificial GBs to permit systematic comparison of experimental and analytical results. Through photoluminescence imaging, we found that the number of dislocation clusters generated around the 〈110〉-oriented GBs was significantly higher than those around the 〈100〉-oriented GBs. The stress analysis revealed that this difference is linked to the maximum shear stress around the GB. However, there were some GBs where dislocation cluster generation was not observed despite the presence of high shear stress. For most of these GBs, the direction of the maximum shear stress in the 12 slip system of silicon crystal was found to be oblique downward to the growth direction, which appears to inhibit dislocation propagation.

Possibilities of developing technology for generating electricity using photovoltaic modules

The purpose of this paper is to present the most commonly used types of photovoltaic panels and principles of their operation. Mono- and polycrystalline cells are presented, with their advantages and disadvantages indicated. The following section describes the process of obtaining electricity by using the photovoltaic and thermoelectric phenomena occurring in cells. Then, the structure and principle of operation of dye cells, thin-film cells and fourth-generation cells were presented on the example of cells using the Schottky junction to generate energy. The article also presents the method of obtaining single crystals of silicon, developed by Jan Czochralski, who lived at the turn of the 19th and 20th centuries. The method he developed laid the foundations for the development of modern integrated circuits - it was a milestone in the development of electronics.

Large-Angle Rocking Beam Electron Diffraction of Large Unit Cell Crystals Using Direct Electron Detector.

We report a large-angle rocking beam electron diffraction (LARBED) technique for electron diffraction analysis. Diffraction patterns are recorded in a scanning transmission electron microscope (STEM) using a direct electron detector with large dynamical range and fast readout. We use a nanobeam for diffraction and perform the beam double rocking by synchronizing the detector with the STEM scan coils for the recording. Using this approach, large-angle convergent beam electron diffraction (LACBED) patterns of different reflections are obtained simultaneously. By using a nanobeam, instead of a focused beam, the LARBED technique can be applied to beam-sensitive crystals as well as crystals with large unit cells. This paper describes the implementation of LARBED and evaluates the performance using silicon and gadolinium gallium garnet crystals as test samples. We demonstrate that our method provides an effective and robust way for recording LARBED patterns and paves the way for quantitative electron diffraction of large unit cell and beam-sensitive crystals.

Schottky Diode Leakage Current Fluctuations: Electrostatically Induced Flexoelectricity in Silicon.

Nearly four decades have passed since IBM scientists pioneered atomic force microscopy (AFM) by merging the principles of a scanning tunneling microscope with the features of a stylus profilometer. Today, electrical AFM modes are an indispensable asset within the semiconductor and nanotechnology industries, enabling the characterization and manipulation of electrical properties at the nanoscale. However, electrical AFM measurements suffer from reproducibility issues caused, for example, by surface contaminations, Joule heating, and hard-to-minimize tip drift and tilt. Using as experimental system nanoscale Schottky diodes assembled on oxide-free silicon crystals of precisely defined surface chemistry, it is revealed that voltage-dependent adhesion forces lead to significant rotation of the AFM platinum tip. The electrostatics-driven tip rotation causes a strain gradient on the silicon surface, which induces a flexoelectric reverse bias term. This directional flexoelectric internal-bias term adds to the external (instrumental) bias, causing both an increased diode leakage as well as a shift of the diode knee voltage to larger forward biases. These findings will aid the design and characterization of silicon-based devices, especially those that are deliberately operated under large strain or shear, such as in emerging energy harvesting technologies including Schottky-based triboelectric nanogenerators (TENGs).

Optimizing CZ Silicon Crystal Growth: Algorithmic Approach for Defect Minimization

Optimizing CZ Silicon Crystal Growth: Algorithmic Approach for Defect Minimization

Effect of Crystal Rotation on Melt Convection and Resistivity Distribution in 200 mm Floating Zone Silicon Single Crystal Growth.

Floating silicon is particularly suitable for the production of power devices and detectors due to its high purity and high resistivity. However, when the crystal diameter increases to 200 mm, the inhomogeneous distribution of dopants in the radial direction of the crystal becomes an important factor affecting the quality of the crystal. In this paper, the melt flow and crystal interface dopant distribution of 200 mm floating zone silicon under different crystal rotation modes using 2D axisymmetric models was calculated. In the simulation, the crystal rotates unidirectionally clockwise or alternates between clockwise and counterclockwise rotations and is compared with the corresponding experimental results. The results of alternate rotation show a significant improvement in the distribution of resistivity, which is explained from the perspective of melt flow, providing ideas for the industrial production of high-quality FZ silicon crystals.

Development of a mathematical model of a collinear filter based on Quartz (SiO2) and its practical implementation

Purpose of the work. Development and testing of a theoretical model of an acousto-optic quasi-collinear tunable filter on crystalline quartz, operating in the spectral range of 0.25-0.4 microns with a spectral resolution of 0.2 nm.Methods. The paper analyzes the basic properties of acousto-optic tunable filters based on crystals of various classes. Based on literature analysis and calculations, an experimental AOTF model was proposed and practically implemented. The study of the physical properties of light filtration on an α-SiO2 crystal was carried out using an experimental method.Practical studies of the spectral tuning of the device at experimental optical frequencies were carried out in the proposed ultrasonic standing wave system in accordance with the tuning characteristic. Based on known experimental data, a theoretical model for describing the passband taking into account piezoelectric effects is proposed.Results. The influence of crystal anisotropy on their acoustoelectric properties is shown. The optimal crystallographic parameters for the operation of filters on a silicon oxide crystal have been determined. A computer model of AOTF has been developed, implemented on the basis of numerical calculations in the Wolfram Mathematica environment. It was experimentally revealed that in the red part of the spectrum under study, the maximum intensity of the frequencies of diffracted light is observed, which corresponds to those closest to the natural frequencies of the piezoelectric transducer, while at the same time, in the blue and violet spectra, the lowest transmission was observed. Practical studies have confirmed that the broadening of the filter passbands occurs due to an increase in the divergence of light.Conclusions. A mathematical model of an acousto-optic quasi-collinear tunable filter on crystalline quartz was substantiated and developed, on the basis of which the calculation of the AOTF operating in the spectral range of 0.25 - 0.4 μm with a spectral resolution of about 0.2 nm was performed.

Discovery of novel silicon allotropes with optimized band gaps to enhance solar cell efficiency through evolutionary algorithms and machine learning

In the pursuit of advancing solar energy technologies, this study presents 20 direct and quasi-direct band gap silicon crystalline semiconductors that satisfy the Shockley-Queisser limit, a benchmark for solar cell efficiency. Employing two evolutionary algorithm-based searches, we optimize structures and calculate fitness function using the DFTB method and Gaussian approximation potential. Following the preselection of structures based on energy considerations, we further optimize them using PBEsol DFT. Subsequently, we screen the structures based on their band gap, employing a DFTB method tailored for band gap calculation of silicon crystals. To ensure accurate band gap determination, we employ HSE and GW methods. To validate the structural stability, we employ phonon analysis via linear regression algorithm applied to PBEsol DFT data. Significantly, the structures unveiled in this study are of great importance due to their proven stability from both mechanical and dynamic perspectives. Furthermore, the ductility and low density of certain structures enhance their potential application. We examine the optical properties by studying the imaginary part of the dielectric function by solving the Bethe–Salpeter Equation on top of GW approximation. By calculating the SLME, we achieve an efficiency of 32.7% for Si22 at a thickness of 500 nm. Moreover, the study harnesses various machine learning algorithms to develop a predictive model for the band gap energy of these silicon structures. Input data for machine learning models are derived from structural MBTR and SOAP descriptors, as well as DFT outputs. Notably, the results reveal that features extracted from DFT outperform the MBTR and SOAP descriptors.

Laser explosion-based fast lithography to modulate silicon crystals

Laser direct lithography allows for the maskless production and alignment of nanocrystals. However, laser-induced crystal growth requires a complex process of nucleation followed by growth that takes a long time, resulting in low efficiency. Here, we used a laser explosion to pre-grow silicon seed crystals in a silicon precursor solution, simplified crystal growth and increased the lithography efficiency. By operating the laser exposure time, the crystal size can be controlled, and even inducing the fusion of nanocrystalline into single crystal grains. As a proof of concept, we fabricated silicon quantum dot architectures with a direct lithography rate of 350 µm/s by this strategy, achieving quantum dot growth within ∼0.54 milliseconds time in an ambient environment. The silicon quantum dots could be contact and fusion through a laser modulation, ultimately forming single silicon microcrystals within the architectures of lithography.

Multiple scattering of 855 MeV electrons in amorphous and crystalline silicon: Simulations versus experiment

The angular distribution function of multiple scattering experienced by 855MeV electrons passing through an amorphous silicon plate and an oriented silicon crystal has been studied by means of relativistic molecular dynamics simulations using two types of the potentials that describe electron–atom interaction. The differences in the angular distributions of the beam particles in both media are analyzed. The results obtained are compared to the experimental data and to the results of Monte Carlo simulations.

Plasmon‐Enhanced Circular Polarization High‐Harmonic Generation from Silicon

AbstractHigh harmonics of circular polarization can be directly generated by monochromatic circularly polarized incident light owing to the high density and stable structure of crystal media. If the arrangement of multiple coplanar atoms in the unit structure of the crystal exhibits rotational symmetry, the polarization state of the high harmonics generated from the crystal follows specific selection rules that have been observed in the 2D crystal medium. In addition, the geometric symmetry of the coplanar atom distribution is related to the orientation of cubic crystals. This implies that only the polarization along a specific crystal orientation can achieve a selection of high‐harmonic polarization states. However, this is a very weak process in cubic crystals owing to the attenuation of crystal anisotropy to circularly polarized light and the dependence of the electron transition rate on the crystal orientation. In this study, plasmonic nanoantennas are designed on silicon crystal films to enhance this process. The harmonic emission is more than ten times brighter than that without nanoantennas and conformed to the selection rules for high harmonics. The research results offer a new approach for deep­ultraviolet space filtering, carrier control, and the development of compact extreme­ultraviolet light sources.

Simulation of deflection and photon emission of ultra-relativistic electrons and positrons in a quasi-mosaic bent silicon crystal

Abstract A comprehensive numerical investigation has been conducted on the angular distribution and spectrum of radiation emitted by 855 MeV electron and positron beams while traversing a ‘quasi-mosaic’ bent silicon (111) crystal. This interaction of charged particles with a bent crystal gives rise to various phenomena such as channeling, dechanneling, volume reflection, and volume capture. The crystal’s geometry, emittance of the collimated particle beams, as well as their alignment with respect to the crystal, have been taken into account as they are essential for an accurate quantitative description of the processes. The simulations have been performed using a specialized relativistic molecular dynamics module implemented in the MBN Explorer package. The angular distribution of the particles after traversing the crystal has been calculated for beams of different emittances as well as for different anticlastic curvatures of the bent crystals. For the electron beam, the angular distributions of the deflected particles and the spectrum of radiation obtained in the simulations are compared with the experimental data collected at the Mainz Microtron facility. For the positron beam such calculations have been performed for the first time. We predict significant differences in the angular distributions and the radiation spectra for positrons versus electrons.

Асимметричная рентгеновская дифракция ограниченных пучков в кристаллах

Asymmetric dynamic diffraction of confined X-ray beams in crystals has been theoretically studied using Takagi–Taupin equations, including numerical solution using nodal grid and calculations of X-ray fields in Fourier space. We have fulfilled simulation of scattering intensity distribution maps from silicon crystal near reciprocal lattice site depending on size of X-ray beams.

К теории рентгеновской Лауэ дифракции в термомиграционном кристаллическом канале с легирующей примесью

X-ray Laue diffraction in a silicon crystal with Si(Al) thermomigration channels has been theoretically considered. Based on the model of elastic fields of atomic displacements in the channel, expressions for the distribution of strains have been obtained to describe diffraction in the Laue geometry. A numerical calculation of the X-ray scattering intensity distribution near a reciprocal lattice point has been performed. The difference between diffraction in a perfect and strained crystal has been shown.

Defect behavior during growth of heavily phosphorus-doped Czochralski silicon crystals. I. Experimental study

Defect behavior during growth of heavily phosphorus-doped Czochralski silicon crystals. I. Experimental study

Defect behavior during growth of heavily phosphorus doped Czochralski silicon crystals (II): Theoretical study

Defect behavior during growth of heavily phosphorus doped Czochralski silicon crystals (II): Theoretical study

A stress-induced source of phonon bursts and quasiparticle poisoning

The performance of superconducting qubits is degraded by a poorly characterized set of energy sources breaking the Cooper pairs responsible for superconductivity, creating a condition often called “quasiparticle poisoning”. Both superconducting qubits and low threshold dark matter calorimeters have observed excess bursts of quasiparticles or phonons that decrease in rate with time. Here, we show that a silicon crystal glued to its holder exhibits a rate of low-energy phonon events that is more than two orders of magnitude larger than in a functionally identical crystal suspended from its holder in a low-stress state. The excess phonon event rate in the glued crystal decreases with time since cooldown, consistent with a source of phonon bursts which contributes to quasiparticle poisoning in quantum circuits and the low-energy events observed in cryogenic calorimeters. We argue that relaxation of thermally induced stress between the glue and crystal is the source of these events.

Step height measurement of monoatomic silicon crystal lattice steps with a commercial atomic force microscope

Abstract Precise control of advanced materials relies on accurate dimensional metrology at the sub-nanometre scale. At this scale, the accuracy of scanning probe microscopy (SPM) has been limited by the lack of traceable transfer standard artefacts with calibration structures of suitable dimensions. With the adoption in 2019 of the silicon crystal lattice spacing as a secondary realization of the metre in the International System of Units (SI), SPM users have direct access to a realization of the SI metre at the sub-nanometre level by means of the step height of self-assembled monatomic lattice steps that can form on the surface of silicon crystals. A key challenge of successfully adopting this pathway is establishing the need for established protocols to minimize measurement errors and artifacts in routine laboratory use.
In this study, step height measurements of monoatomic lattice steps in an ordinal/staircase structure on a Si(111) crystal surface have been derived from images acquired with a commercially available, research-level atomic force microscope (AFM). Measurement results derived from AFM images using three different SPM image processing and analysis software packages are compared. Significant sources of measurement uncertainty are identified; principally the contribution from the dependence on scan direction. The calibration of the
AFM derived from this measurment was used to traceably measure the sub-nanometre lattice steps on a silicon carbide crystal surface to demonstrate the viability of this calibration pathway.

Transformer-Based Neural-Network Quantum State Method for Electronic Band Structures of Real Solids.

Recent advancements in neural networks have led to significant progress in addressing many-body electron correlations in small molecules and various physical models. In this work, we propose QiankunNet-Solid, which incorporates periodic boundary conditions into the neural network quantum state (NNQS) framework based on generative Transformer architecture along with a batched autoregressive sampling (BAS) method, enabling the effective ab initio calculation of real solid materials. The accuracy of this method is demonstrated in one-, two-, and three-dimensional periodic systems, with results comparable to those of full configuration interaction and coupled-cluster method, even in the strongly correlated regime. Furthermore, we compute the band structures and density of states for silicon crystal. The successful incorporation of periodic boundary conditions into the NNQS framework through QiankunNet-Solid opens up new possibilities for the accurate and efficient study of electronic structure properties in solid-state physics.

TRENDS OF THE MICROWAVE PHOTONIC RADARS

Today, the world's leading countries are intensively working on the development of new generation radars - microwave photonic radars. Microwave photonic radars make it possible to significantly reduce the mass and size characteristics of radar stations, to increase the information capability and range of target detection due to the reduction of losses in long communication lines when using optical fiber, to ensure high immunity due to the significantly lower sensitivity of optical-electronic equipment and fiber-optic lines of communication connection to external electromagnetic influences. Microwave photonics provides wide bandwidth, flat response, low loss transmission, multi-dimensional multiplexing, ultra-fast analog signal processing and immunity to electromagnetic interference. Radar implementation in the optical domain can provide better resolution, coverage, and speed performance, which would be difficult to implement with traditional electronics. The review article examines the state of development and system architectures of such photonic radars as optoelectronic hybrid radars, all-optical radars, multifunctional microwave photonic radar systems, distributed microwave photonic radars, software-defined radars, and cognitive radars. New technologies in this field and possible future directions of research are discussed. As an example, a broadband microwave photon radar reproduced on the basis of a microcircuit is considered. The broadband signal generator and receiver are built into the silicon crystal on the insulator. A high-precision distance measurement with a resolution of 2.7 cm and an error of less than 2.75 mm was obtained. Visualization of multiple targets with complex profiles has been implemented. But the performance of most integrated microwave photonic chips is not yet satisfactory for practical radar applications. Monolithic integration of key microwave photonic subsystems is also not mature enough for practical applications, so hybrid integration of devices fabricated on their optimal integration platforms is of practical interest. At present, indium phosphide, silicon nitride and silicon on insulator are the three leading platforms for photonic integration