Si Doping Research Articles

Enhanced Stability of SiZTO TFT Under Positive Voltage and Light Negative Voltage Stress and Modified Hysteresis of the CNTs/SiZTO CMOS Inverter by Si Doping

Enhanced Stability of SiZTO TFT Under Positive Voltage and Light Negative Voltage Stress and Modified Hysteresis of the CNTs/SiZTO CMOS Inverter by Si Doping

Impact of Si concentration on microstructure and high temperature oxidation behavior of IN718 coating by plasma cladding: An experimental and first principle study

To improve the properties of IN718 coatings, Si-modified IN718 coatings with an equiaxed structure and enhanced high-temperature oxidation resistance were fabricated by plasma cladding in this paper. The addition of Si aggravated the precipitation of the Laves phase and Cr/Nb segregation. First-principles calculations revealed that the increase in repulsive forces between NbFe atoms and CrNi atoms is the essential reason for the promotion of Cr/Nb segregation. The hardness of IN718 increases with Si addition, mainly attributed to grain refinement and dislocation strengthening. High-temperature oxidation experiments revealed that the 3Si-IN718 coating generated a double oxide layer at 1000 °C, with Cr2O3 in the external layer and SiO2 in the internal layer; therefore, the oxidation resistance of the coating was greatly enhanced. Si addition significantly reduced the internal oxidation of Al/Nb and cracking of the oxide layer. However, Si has a modest contribution to oxidation resistance, and the oxide layers were all Cr2O3 at 900 °C. According to the thermodynamic calculations, the elemental activity of Si only increased significantly above 900 °C, which may be the reason for the different results at different experimental temperatures. Calculations of surface adsorption illustrate that Si doping enhances the ability of the Ni-Fe-Cr surfaces to bind O atoms and raises the potential barrier for O atoms to diffuse into the sublayer, thereby enhancing the resistance of the IN718 coating to high-temperature oxidation.

Role of silicon on the conductivity GaSb surface: A first-principles study

Gallium antimonide (GaSb) has exceptional semiconductor properties, making it a promising material for various applications, leading to extensive theoretical and experimental studies. The prevalence of GaSb antisite defects in unintentionally doped GaSb leads to intrinsic p-type conductivity, placing a limitation on its utility. Introducing dopants as electron donors to compensate for the vacancies induced by GaSb antisite is viewed as a feasible strategy to ameliorate this issue. This study explores the transformation and enhancement of GaSb conductivity by analyzing the mechanism of Si doping using first-principles calculations. The calculated results show, the GaSb(001) surface with GaSb antisite exhibits unintentional p-type conductivity. When Si as a dopant source, GaSb-3SiGa complex exhibits n-type conductivity. The pure GaSb(001) surface exhibits intrinsic conductivity, and when Si atoms are doped into the system, it only exhibits n-type conductivity. Taken together, the above observations suggest that Si, as an amphoteric dopant, can serve as an n-type dopant for GaSb. Additionally, the upward shift of the Fermi level upon the incorporation of Si atoms exhibits a consistent trend, irrespective of the presence of the GaSb antisite. Furthermore, charge analysis indicates that the conduction band electron count increases, resulting in an improvement of conductivity. This study opens a new avenue for the preparation of potential high-performance GaSb-based semiconductor devices.

Mechanism study on gas-based reduction swelling behavior of ultra-high grade pellets

Utilizing super-concentrate for direct hydrogen reduction in pelletizing which decrease energy consumption and improve smelting quality are critical steps towards achieving the dual carbon goal. The reduction swelling behavior and its corresponding mechanism of ultra-high-grade pellets were studied from multi-dimensions combing visualization detection, micromorphological analysis, and first-principles molecular dynamics simulation in present work. The results showed that for the reduction no matter in CO or H2 atmosphere, the ultra-high grade pellets expand abnormally. Whereas the increase of SiO2 content and the selection of H2 atmosphere can effectively inhibited the reduction swelling behavior of pellets, while Al2O3 content had only a slight effect. The cause of catastrophic expansion was related to the various formation of new-born iron that it exhibited angular during CO reduction while became flatter with SiO2 addition or by H2 reduction. The simulation results were validated the accuracy since the structure and energy changes during iron oxide reduction were corresponding to the experimental observations. C and Fe mainly formed chemical bonds while H and Fe primary produced physical adsorption during FexO reduction. Combing the comprehensive effect of adsorption energy, electrostatic force, and energy change, it was tended to create iron whiskers by CO reduction contrary to H2 reduction. It was conductive to generate iron whisker after Si doped in FexO. However, the decrease of pellets RSI with SiO2 addition in H2 reduction was caused by the increase of pellet porosity, which provided space for the growth of iron whisker. With the increase of Si doping amount in CO reduction, iron whiskers gradually changed from thin to chunky, resulting in more uniform growth of iron whiskers and uniform stress, which brought about a decrease in pellet reduction expansion rate contrarily.

DFT based atomic modeling and Analog/RF analysis of ferroelectric HfO2 based improved FET device

In this study, we systematically investigated the Analog/RF and linearity parameter of SM DGNCFET (single metal double gate negative capacitance field effect transistor) and DM DGNCFET (double metal double gate negative capacitance Field effect transistor) with the help of Cogenda Visual TCAD simulator, and also demonstrated the enhancement in the electronic and optical properties of Si-doping bulk structure by using the Quantum ATK. The analog parameters are enhanced for SM DGNCFET such better performance of switching ratio 279 times better, DIBL 54% lower, SS decay, and some other improved parameter transconductance, TGF and Radio frequency parameter is also enhanced, transconductance frequency product (TFP) for improving reliability and stability of device. Linearity parameters like that second and third order transconductance (gm2, g m3), voltage intercept point for 2nd, 3rd. Tran Blaha modified Becke Johnson (TB-mBJ) approxiamation gives the accurate band gap of crystal. In DFT based atomic study, 12.5% of Si doping in bulk structure reveals better results for ferroelectric HfO2 based crystal in the direct band gap of bandstructure is zero, Density of state (DOS) is also improved conductivity for Si doping crystal. Hence, Si doping in crystal structure is also better for conductivity.

Tuning the Structural, Electronic, and Optical Properties of Monolayer Graphene through Heteroatom Doping: A First-Principles Study with Future Light Sensing Applications

This study explores the effects of Si and Si-P heteroatoms doping and co-doping on a monolayer graphene surface through density functional analysis. The results suggest that doping with Si and co-doping with Si-P significantly alters the bonding arrangement of the atoms surrounding the graphene sheet. Additionally, the surface of the graphene material had a high concentration of electrons in both Si doping and Si-P co-doping, based on electron population analysis. The HOMO–LUMO gap of graphene sheets was found to decrease in the following order: pristine graphene sheet > Si-doped graphene sheet > Si-P co-doped graphene sheet. Furthermore, a TD-DFT study revealed that the absorption wavelength of Si and Si-P co-doped graphene systems had a greater shift to a lower range compared to pristine graphene. The order of decreasing absorption wavelength is Si-P co-doped graphene, Si doped graphene, and pristine graphene. These materials are suggested to have a high potential for photodetector applications due to their broad absorption range.

Upgradation, product analysis and engine performance of hydrocarbon fuels produced through pyrolysis of thermoplastic polymers with Si and ZSM-5 modified catalysts

Waste plastic mitigation is one of the major concerns for achieving a sustainable environment. The present study reported the conversion of mixed waste plastics into hydrocarbon fuels through catalytic pyrolysis using DOL, SiDOL, ZSM-5, and ZSMDOL catalysts. Doping of Si and ZSM-5 enhanced the surface area as well as improved catalytic activity. The NMR analysis confirmed that pyro-oil contains 8.31–12.61, 17.53–29.12, and 62.38–69.86 (v/v)% of aromatics, olefins, and paraffin's hydrocarbons, respectively. FTIR analysis identified the presence of alkane, alkene, and aromatic hydrocarbons. The mass spectroscopy analysis revealed that pyro-oil contained a lower range (<C12) of hydrocarbon (up to ∼89%) when the catalyst was used. The fluidity properties such as density, viscosity, and pour point were reduced significantly in the catalytic pyro-oil due to the further cracking of intermediate hydrocarbons formed during the pyrolysis. The pour point was found to be the lowest (below -40 °C) for pyro-oil obtained with ZSM-5 catalyst. The highest calorific values of ∼50.9 MJ/kg and lowest carbon residues of ∼0.11 wt% were estimated for catalytic pyro-oils. The DI diesel engine performance showed that catalytic pyro-oils had better engine performance and combustion process compared to other fuels. Also, the emissions of harmful gases such as CO, HC, and NOx were found to be lower than commercial diesel when pyro-oil was blended with CD.

Contribution of Si to the precipitation of γ'-phase in high Al content IN718 coatings and the phase transformation of α-Al2O3 during high temperature oxidation

The Al–Si composite-modified IN718 alloy has not been studied in depth thus far. In this paper, an Al–Si composite-modified IN718 coating was successfully fabricated by plasma cladding, and it was found that Al–Si increases the composition supercooling of the alloy melt, increases the proportion of equiaxed crystals in the coating, and greatly enhances the hardness of the coating through the precipitation of a large area of the γ'-phase. The changes in the properties of the γ and γ'-phases before and after Si doping were clarified by first-principles studies. High-temperature experiments show that the Al–Si IN718 coating has excellent resistance to high-temperature oxidation and that the addition of Si promotes the phase transformation of α-Al2O3 in the early stages of oxidation.

Resolution of Virtual Depth Sectioning from Four-Dimensional Scanning Transmission Electron Microscopy.

One approach to three-dimensional structure determination using the wealth of scattering data in four-dimensional (4D) scanning transmission electron microscopy (STEM) is the parallax method proposed by Ophus et al. (2019. Advanced phase reconstruction methods enabled by 4D scanning transmission electron microscopy, Microsc Microanal25, 10-11), which determines the scattering matrix and uses it to synthesize a virtual depth-sectioning reconstruction of the sample structure. Drawing on an equivalence with a hypothetical confocal imaging mode, we derive contrast transfer and point spread functions for this parallax method applied to weakly scattering objects, showing them identical to earlier depth-sectioning STEM modes when only bright field signal is used, but that improved depth resolution is possible if dark field signal can be used. Through a simulation-based study of doped Si, we show that this depth resolution is preserved for thicker samples, explore the impact of shot noise on the parallax reconstructions, discuss challenges to making use of dark field signal, and identify cases where the interpretation of the parallax reconstruction breaks down.

High resistive buffer layers by Fermi level engineering

An efficient carrier compensation mechanism in semiconductor layers by Fermi-level engineering is demonstrated using the modulation-doping of a deep acceptor and a shallow donor. The punch-through of the depletion region across the whole stack of modulation-doped layers shifts the Fermi level closer toward the midgap position, resulting in the compensation of residual background free carriers. The method represents an alternative to achieve semi-insulating properties in semiconductor materials where a suitable deep acceptor or donor state at the midgap position is not available. We demonstrate the applicability of the concept with a commercially important GaN case study using carbon (deep acceptor) and Si (shallow donor) doping. A strong enhancement of breakdown field strength and reduced charge pileup effects are observed due to the efficient pinning of the Fermi level.

Elastic, electronic and thermodynamic properties of β-SiO2 doped by Ar: A first-principles investigation

First-principles computations based on density functional theory (DFT) were used to investigate the doping formation energy, elastic constants, population analysis, and thermodynamic properties of the perfect and doped structures of β-SiO2. We find that the Ar interstitial doping structure is more easily formed but is mechanically unstable (C44 < 0). Derived mechanical parameters such as bulk modulus, shear modulus, and Young's modulus indicate that introducing the Ar atom reduces the β-SiO2 structure's ability to resist deformation and strain. Meanwhile, according to the results of the elastic anisotropy parameters (A1, A2, and A3 are not equal to 1), the perfect and Ar-substituted doping structures of β-SiO2 are anisotropic. The electronic properties of the structures were studied using population analysis, introducing the Ar atom increases the interatomic bonding length. Meanwhile, the O-Ar bond shows anti-bonding characteristics due to the negative population value of the bond. Furthermore, to investigate the stability of the doping structures, the binding energy of the structures was computed and the results indicate that the Ar-substituted O doping structure is more stable than the Ar-substituted Si doping structure.

The surface tension of Ga2O3 melt measured by a drop-weight method in an optical floating-zone furnace

The surface tension of Ga2O3 melt is successfully measured using a drop-weight method in an optical floating-zone furnace that we have developed. The method is verified to be feasible by measuring the surface tension value of TiO2 melt and then comparing it with values in previous reports determined by other methods. We find that the surface tension of Si-doped Ga2O3 melt increases with the decrease in the Si doping concentration and reaches 527.9 mN m−1 for pure Ga2O3 melt. The surface tension of the unintentionally doped Ga2O3 melt is also measured to be 519.3 mN m−1 in the presence of some common contaminants appearing in Czochralski and edge-defined film-fed growth methods, including Ir, Al, and Si.

Changing of the Interfacial Contacts and Shear Behaviors between a-C Films Caused by Si Doping

Changing of the Interfacial Contacts and Shear Behaviors between a-C Films Caused by Si Doping

Trapping Layers Prevent Dopant Segregation and Enable Remote Doping of Templated Self-Assembled InGaAs Nanowires.

Selective area epitaxy is a promising approach to define nanowire networks for topological quantum computing. However, it is challenging to concurrently engineer nanowire morphology, for carrier confinement, and precision doping, to tune carrier density. We report a strategy to promote Si dopant incorporation and suppress dopant diffusion in remote doped InGaAs nanowires templated by GaAs nanomembrane networks. Growth of a dilute AlGaAs layer following doping of the GaAs nanomembrane induces incorporation of Si that otherwise segregates to the growth surface, enabling precise control of the spacing between the Si donors and the undoped InGaAs channel; a simple model captures the influence of Al on the Si incorporation rate. Finite element modeling confirms that a high electron density is produced in the channel.

In‐Plane AlN‐based Actuator: Toward a New Generation of Piezoelectric MEMS

AbstractA novel design that utilizes aluminum nitride (AlN) piezoelectric thin films deposited on vertical surfaces for lateral motion and sensing is a step toward emerging multi‐axial microelectromechanical systems (MEMS). This work demonstrates the fabrication process and potential applications of an in‐plane moving piezoactuator. The actuator is excited using the inverse piezoelectric effect of the AlN thin film grown on the vertical surfaces of a Si cantilever. Lateral motion of the actuator is enabled when a voltage is applied between the top and bottom electrodes of the device, which are highly doped Si and titanium nitride thin film. The motion of the actuator is captured using scanning electron microscope.

Finite temperature effects on the structural stability of Si-doped HfO2 using first-principles calculations

The structural stabilities of the monoclinic and tetragonal phases of Si-doped HfO2 at finite temperatures were analyzed using a computational scheme to assess the effects of impurity doping. We proposed a method that the finite temperature effects, i.e., lattice vibration and impurity configuration effects, are considered. The results show that 6% Si doping stabilizes the tetragonal phase at room temperature, although a higher concentration of Si is required to stabilize the tetragonal phase at zero temperature. These data indicate that lattice vibration and impurity configuration effects are important factors determining structural stability at finite temperatures.

In Silico Investigation of Al, Si and Ge Dopants Effect on Structural and Electrical Properties of Pristine B12N12 Nanocage Toward Acrolein Adsorption

In Silico Investigation of Al, Si and Ge Dopants Effect on Structural and Electrical Properties of Pristine B12N12 Nanocage Toward Acrolein Adsorption

High-temperature oxidation and self-healing behavior of SiC and Ni Co-dispersed into Al2O3 matrix composite

High-temperature oxidation behavior and recovery of mechanical strength are investigated on 5 vol%Ni/Al2O3 self-healing ceramics with 1 vol% SiC co-dispersion (SiC + Ni/Al2O3). For oxidation experiment, samples were heat-treated in the temperature range of 1200–1350 °C for 24–168 h in air. For self-healing experiment, surface cracks were introduced by the Vickers indentation and then heat-treated at 1000–1300 °C for 1 and 48 h in air. The internally oxidized zone (IOZ) on SiC + Ni/Al2O3 is composed of NiAl2O4 and Al2O3 matrix. Its thickness is smaller than that of Ni/Al2O3 under the same heat-treatment conditions. The apparent activation energy on growth of IOZ for SiC + Ni/Al2O3 is approximately 680 kJ/mol, indicating that grain boundary diffusion of oxygen ion in Al2O3 is rate-controlling. Al2O3 grain boundary diffusion of oxygen ion would be suppressed by SiO2 doping via oxidation of SiC co-dispersion. Surface cracks introduced by the Vickers indentation filled with NiAl2O4. The crack disappearance rates are comparable to that of Ni/Al2O3 with Y or Si dopants. Apparent activation energy of self-healing is approximately 350 kJ/mol and its value is similar with grain boundary diffusion of Ni ions at Al2O3 matrix. Bending strengths of as-sintered and as-cracked of SiC + Ni/Al2O3 samples are 501 MPa and 114 MPa, respectively. Samples heat-treated at 1200 °C for 6 h shows bending strength up to 550 MPa, resulting in no disadvantage on the self-healing effect for SiC co-dispersion. Both of self-healing function and resistance of high-temperature internal oxidation is achieved on SiC + Ni/Al2O3.

Doping Properties of GaAs Film Grown by Molecular Beam Epitaxy

In order to make GaAs-based devices widely applicated in high-frequency and mobile communication, we use molecular beam epitaxy to grow GaAs thin films, and achieve the enhancement of GaAs thin film mobility and the increase of band width by doping control techniques. In our experiments, we use Si as dopant source to obtain GaAs thin films with high doping concentration, and we prepare and test the samples with different dopant source temperatures to achieve the regulation of the band gap, film luminescence intensity, surface roughness and mobility. The doping concentration of the prepared GaAs thin film layer was achieved at 1250 °C with Si doping source of 2.07 × 1018 cm−3, the mobility was 2097 cm2/V·s, and the photoluminescence(PL) intensity was increased by 100 times compared with the non-doped film.

The impact of Si and Cu doping upon the sensing capability of BN nano-tube in detecting diazomethane

The hybrid exchange-correlation functional B3LYP is used to see how Si and Cu-doping impacts upon the sensing capability of a BN nano-tube (BNNT) in detecting diazomethane (DM). The interaction of the pristine BNNT with DM was weak with a sensing response (SR) of roughly 2.7. The adhesion energy for DM reduced from −4.9 to −21.5 kcal/mol after Si and Cu atoms were doped on the surface of the BNNT and also, the SR reduced to 33.1 and 85.8, respectively. The greater atomic radius of Cu compared to Si seemed to be the reason for the greater SR. The recovery time (RT) when DM was desorbed from the surface of the BNNT doped with Cu at 298 K was 4.6 s. We conclude that it is possible to use the Cu-doped BNNT as a highly sensitive sensor to detect DM with a short RT.