Impurity Atoms In Silicon Research Articles

Strain-Induced asymmetry and on-site dynamics of silicon defects in graphene

• DFT calculations predict two distinct isomers for Si defects in strained graphene. • STEM images capture transitions between distinct Si structures with the same bonding. • Anisotropic strain can be generated and also exposed by Si defects in graphene. In the last decade, the atomically-focused electron beams utilized in scanning transmission electron microscopes (STEMs) have been shown to induce a broad set of local structural transformations in materials, opening pathways for directing material synthesis and modification atom-by-atom. The mechanisms underlying these transformations remain largely unknown, due to the intractability of modeling the myriad of reaction pathways that can be accessed through high-energy electron scattering. The information on materials’ structure and dynamics that can be extracted from STEM images is similarly left underexplored. Here, we report the observation of anomalous on-site dynamics of individual silicon impurity atoms in graphene during STEM imaging. Density functional theory-based structural optimizations of anisotropically-strained molecular nanographenes reveal two distinct (but nearly degenerate) stable structures for four-fold coordinated silicon impurities, where interconversion between the two structures manifests slight changes of the silicon position within the lattice site. Implications for defect-based strain engineering in graphene are discussed.

Optical and microstructural characterization of Micro-LED with sidewall treatment

The traditional influence on the sidewall damage of Micro-LED was mostly focused on the research of I-V-L. In this paper, we discussed the influence of Micro-LED sidewall damage from the perspective of optical and microstructural characterization. Scanning electron microscopy showed that the Micro-LED structure with smaller size was more irregular after inductively coupled plasma etching. High-resolution transmission electron microscopy and energy dispersive x-ray spectroscopy analysis showed that the area of the upper and lower regions of the quantum well was inconsistent, there was about 2 nm lattice disorder on the surface of the sidewall of the mesa, and oxygen and silicon impurity atoms were enriched. For optical characterization, a method combining laser scanning confocal microscopy and photoluminescence (PL) was proposed to evaluate the optical performance of the mesa. The results showed that the luminescence of Micro-LED mesa was uneven, the luminous intensity at the edge of the mesa was reduced by more than 65%, and the luminous wavelength was shifted by several nanometers. Finally, we optimized the sidewall treatment process, effectively improved the performance of Micro-LED devices by combining tetramethylammonium hydroxide treatment and SiO2 passivation, and increased the luminous intensity of Micro-LED 2 μm away from the edge by about 4.7 times and PL uniformity was greatly improved. These results provided an available reference for the development of Micro-LED.

Особенности электрофизических параметров кремния, легированного последовательно примесными атомами фосфора и бора

Silicon samples sequentially doped with impurity atoms of phosphorus and boron were studied. These investigations make it possible to study the interaction and distribution of phosphorus and boron impurity atoms in silicon. It has been established that, in such silicon samples, the mobility of electrons and holes changes. From the analysis of the obtained results, it was shown that boron atoms change the type of conductivity of the material to a depth of 2 μm due to the compensation of phosphorus atoms, which are 4 times higher than the concentration of boron in silicon.

Formation of Complexes of Phosphorus and Boron Impurity Atoms in Silicon

Formation of Complexes of Phosphorus and Boron Impurity Atoms in Silicon

Features of the electrophysical parameters of silicon serially doped with impurity atoms of phosphorus and boron

Silicon samples sequentially doped with impurity atoms of phosphorus and boron were studied. These investigations make it possible to study the interaction and distribution of phosphorus and boron impurity atoms in silicon. It has been established that, in such silicon samples, the mobility of electrons and holes changes. From the analysis of the obtained results, it was shown that boron atoms change the type of conductivity of the material to a depth of 2 μm due to the compensation of phosphorus atoms, which are 4 times higher than the concentration of boron in silicon. Keywords: semiconductor, silicon, phosphorus, boron, alloying, mobility, diffusion, concentration.

Effect of the diffusion temperature on interaction of clusters with impurity atoms in silicon

In this paper, the results of studies of the effect of the diffusion temperature on interaction of clusters of manganese atoms with the sulfur ones have been presented. It has been shown that the electrical parameters of the samples simultaneously doped with sulfur and manganese completely coincide with the parameters of the initial material, i.e. as if they do not contain not only sulfur and manganese, but also thermodonors are not formed. The obtained results make it possible to exclude the possibility of gettering of impurity atoms or formation of some kind of solid solutions, if taking into account the impurity atoms of manganese and sulfur, which complicates their diffusion in the crystal bulk. It has been established that for the initial p-type silicon with the resistivity close to p ~ 10 Ω·cm, the diffusion temperature of 1100 °C is the most optimal one to form clusters with the maximum participation of the introduced sulfur and manganese atoms.

Ab Initio Calculation of the Interaction of an Edge Dislocation with Transition Metal Impurity Atoms in Silicon

Ab Initio Calculation of the Interaction of an Edge Dislocation with Transition Metal Impurity Atoms in Silicon

Structure of defects in semiconductor crystalline cubic boron nitride. A microstructural and micro analytical investigation

Previous electron spin resonance investigations correlated with data from cathodoluminscence and photoluminescence measurements have shown that impurity ions consisting mainly of isotopes with zero nuclear moments are involved in the structure of the observed paramagnetic point defects. In the present microstructural and compositional investigation we demonstrate that oxygen, carbon and silicon impurity atoms exhibiting low natural content of isotopes with non-zero nuclear spin are indeed present in cBN crystallites selected from amber coloured BORAZON CBN400 and CBN 500 super abrasive powders, as well as in the black coloured BORAZON CBN1000 and CBN Type 1. It is also shown that aggregates of impurity atoms are present next to the extended cBN lattice defects, which could explain the non-uniform distribution of the electro- and opto-active impurities reported in a spectroscopy investigation.

Electron-nuclear spin dynamics of Ga2+ paramagnetic centers probed by spin-dependent recombination: A master equation approach

Similar to nitrogen-vacancy centers in diamond and impurity atoms in silicon, interstitial gallium deep paramagnetic centers in GaAsN have been proven to have useful characteristics for the development of spintronic devices. Among other interesting properties, under circularly polarized light, gallium centers in GaAsN act as spin filters that dynamically polarize free and bound electrons reaching record spin polarizations (100\%). Furthermore, the recent observation of the amplification of the spin filtering effect under a Faraday configuration magnetic field has suggested that the hyperfine interaction that couples bound electrons and nuclei permits the optical manipulation of its nuclear spin polarization. Even though the mechanisms behind the nuclear spin polarization in gallium centers are fairly well understood, the origin of nuclear spin relaxation and the formation of an Overhauser-like magnetic field remain elusive. In this work we develop a model based on the master equation approach to describe the evolution of electronic and nuclear spin polarizations of gallium centers interacting with free electrons and holes. Our results are in good agreement with existing experimental observations. In regard to the nuclear spin relaxation, the roles of nuclear dipolar and quadrupolar interactions are discussed. Our findings show that, besides the hyperfine interaction, the spin relaxation mechanisms are key to understand the amplification of the spin filtering effect and the appearance of the Overhauser-like magnetic field. Based on our model's results we propose an experimental protocol based on time resolved spectroscopy. It consists of a pump-probe photoluminescence scheme that would allow the detection and the tracing of the electron-nucleus flip-flops through time resolved PL measurements.

Formation of two-dimensional SiNx layers on GaN nonpolar surfaces

Density functional theory calculations were performed to study the adsorption and incorporation of silicon atoms over GaN (112̅0) and GaN(101̅0) aiming to gain insight into epitaxial growth of two-dimensional layers of silicon nitride (SiNx) on the GaN nonpolar surfaces. Results show that the adsorption of silicon atoms on the bridge sites is energetically more favored as compared with other possible adsorption sites. Formation energy calculations indicate that the silicon impurity atoms prefer to incorporate in second or deeper GaN surface layers. However, it is concluded that the incorporation of Si atoms in the Ga-substitutional site is energetically more favorable compared with the N-substitution and Si-adsorption on the top layers. At full coverage, calculations show the formation of two-dimensional SiNx layers on the GaN nonpolar surfaces over the entire range of Ga chemical potentials, in agreement with experimental observations. In addition, the electronic structure of the GaN nonpolar surfaces with Si doping was analyzed and compared with those of undoped surfaces.

A silicon-based surface code quantum computer

AbstractIndividual impurity atoms in silicon can make superb individual qubits, but it remains an immense challenge to build a multi-qubit processor: there is a basic conflict between nanometre separation desired for qubit–qubit interactions and the much larger scales that would enable control and addressing in a manufacturable and fault-tolerant architecture. Here we resolve this conflict by establishing the feasibility of surface code quantum computing using solid-state spins, or ‘data qubits’, that are widely separated from one another. We use a second set of ‘probe’ spins that are mechanically separate from the data qubits and move in and out of their proximity. The spin dipole–dipole interactions give rise to phase shifts; measuring a probe’s total phase reveals the collective parity of the data qubits along the probe’s path. Using a protocol that balances the systematic errors due to imperfect device fabrication, our detailed simulations show that substantial misalignments can be handled within fault-tolerant operations. We conclude that this simple ‘orbital probe’ architecture overcomes many of the difficulties facing solid-state quantum computing, while minimising the complexity and offering qubit densities that are several orders of magnitude greater than other systems.

Interaction of multiply charged manganese nanoclusters with selenium and tellurium atoms in silicon

We have studied interaction of multiply charged manganese nanoclusters with Se and Te impurity atoms in silicon after simultaneous and sequential codoping. The results demonstrate that, after diffusion doping, certain thermal annealing conditions lead to strong interaction of Mn with Se and Te impurities. We have determined the optimal temperature of such interaction, proposed an interaction mechanism, and demonstrated the possibility of the formation of multicomponent nanoclusters of the form Si2Mn2−Se2+ and Si2Mn2−Te2+ in the silicon lattice without considerable distortion of chemical bonds in the silicon lattice.

Structure of La(Fe0.88Si x Al0.12 − x )13 compounds in the paramagnetic state

X-ray diffraction patterns and nuclear gamma resonance spectra of La(Fe0.88SixAl0.12 − x)13 compounds in the paramagnetic state at room temperature have been investigated. It has been found that all samples have a cubic structure of the NaZn13 type, in which Si and Al atoms disorderly substitute for iron in the crystallographic position 96i. An analysis of the Mossbauer spectra using the fitting with doublets with different quadrupole splittings has revealed that the distributions of the aluminum and silicon impurity atoms substituting for iron differ significantly. Aluminum is statistically distributed over nine positions of the 96i type in the generalized coordination sphere of the Fe2 atom, whereas silicon predominantly substitutes for only six of the nine positions.

TEM analysis of (Ni,Fe)Si2 precipitates in Si

AbstractThe present article provides evidence that Fe impurity atoms in silicon can be gathered by NiSi2 precipitates at temperatures near RT via solid‐state diffusion. Mixtures of silicon and silicide grains, resulting from annealing at 800–900 °C, were analysed. High supersaturation (about 1019–1020 atoms/cm3) of metal impurities in Si was achieved locally by incorporation of nickel and iron atoms from silicide grains into silicon grains during ion milling for TEM specimen preparation. Consequently, particles with local densities of 1013–1014 precipitates/cm3 and average volumes of 10−18–10−16 cm3 formed via diffusion and precipitation. Precipitates with an irregular octahedra shape and platelet‐like habit were found at dislocations. Less frequently, precipitates with a regular octahedra shape were observed in undisturbed matrix. HRTEM images and SAD patterns demonstrate that all precipitates have NiSi2 structure. Ni contents were detected for all precipitates by EDX analysis, but accumulated amounts of Fe could only be proven for some precipitates at dislocations. Quantitative EDX‐analysis revealed Fe/(Fe + Ni) ratios between 16 and 30 at% for these ternary precipitates.

Electrically active defects induced by irradiations with electrons, neutrons and ions in Ge-rich SiGe alloys

Results of DLTS and high-resolution Laplace DLTS measurements of electrically active defects induced in phosphorus-doped dilute Ge-rich SiGe (0⩽[Si]⩽6 at%) samples by irradiations with 60Co gamma-rays, fast neutrons and 1–3 MeV Si ions and by ensuing annealing are presented in the work. It has been found that the DLTS spectra of these germanium rich SiGe samples irradiated with gamma-rays are qualitatively similar to the spectra of similarly irradiated Ge samples, which do not contain Si. The DLTS spectra of the gamma-irradiated samples are dominated by the E-center (vacancy–phosphorus pair). This indicates that silicon impurity atoms are not effective traps for vacancies in Ge at room temperature. Further, we have found no evidence for possible interactions of Ge self-interstitial atoms with Si atoms upon room temperature electron irradiation of SiGe samples. The presence of Si impurity atoms does not influence significantly the annealing behavior of the E center in Ge-rich SiGe. Thirty-minute heat treatments of the gamma-irradiated samples at 300 °C have resulted in complete removal of radiation-induced damage. DLTS spectra of the SiGe samples after low dose neutron irradiation resemble those observed after gamma irradiations, however, in the neutron-irradiated samples a few more minor DLTS peaks have been observed. The neutron-radiation-induced defects can be removed by anneals at 300 °C. The situation in ion-implanted material is more complex. Point defects, which dominate the DLTS spectra of electron-irradiated SiGe samples, are not the main electrically active traps in the ion-implanted samples. The Laplace DLTS spectra of the implanted samples show evidence of broader features characteristic of defect clusters. The implantation-induced damage is much harder to remove by heat treatments compared to the radiation-induced one. Significant concentration of electrically active traps remain in SiGe samples implanted with high doses of ions even after anneals at 500 °C.

Shallow donor centers in gallium nitrides

Production processes of electrically active defects in nominally undoped n-GaN irradiated with fast electrons are investigated. It has been demonstrated that the silicon impurity atoms with shallow donor states at EC – 20 meV interact with native defects neither during irradiation nor annealing at elevated temperatures. Two major kinds of defects produced by irradiation in n-GaN are revealed: donor centers at EC – 70 meV and deep acceptors centers. These defects were found to be unstable at T > 200 °C. They can be attributed to the vacancies on the nitrogen and gallium sublattices, respectively.

Disturbance of oxygen by isovalent impurity atoms in silicon

The diagram of electronic levels of A–Si–O–Si–A clusters (where A is carbon, germanium, tin or lead), has been obtained by group-theoretical analysis and molecular orbitals approaches. Three possible forms of Si substitution by isovalent impurity atoms are discussed. A linear A–Si–O–Si–A cluster and the clusters with A located in the second sphere relative to an oxygen atom with formation of a planar trans-configuration and a nonplanar cis-configuration were considered. It has been shown, that all these forms of Si substitution by isovalent impurity atoms lead to the decrease of the force constants and frequencies of local vibrations of Si–O–Si, respectively.

Comparison of effects of sodium and silicon impurities onaluminium grain boundaries by first-principles calculation

We calculate the electronic structure of an Al Σ9(22̄1)/[110] tilt grain boundary with substitutionalsodium or silicon impurity atoms using the first-principlespseudopotential method. For the grain boundary with sodiumimpurities and that with silicon impurities, there existsobvious differences in the relaxed configuration, valence chargedensity and local density of states (LDOS), which indicates adifferent embrittlement-promotion mechanism for these two cases.

Diffusion of self-interstitial atoms in silicon

Self-interstitial atoms are the principal point defects in silicon. These defects influence the diffusion of impurity atoms in silicon and their solubility. A method for the independent determination of the equilibrium concentration and of the diffusivity of these self-interstitials is suggested. In the framework of this approach some experimental results are discussed.

Magnetic relaxation of Fe with various concentrations of Si impurity atoms

We give the experimental results of an investigation of the effect of silicon impurity atoms on magnetic relaxation in iron.