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It is of great interest to synthesize boron carbide nanomaterials and explore their novel properties. We reported the synthesis of belt-like Si-doped boron carbide nanomaterials at a low temperature of 1500 °C with no catalyst. The structures and formation mechanism were investigated. Broad photoluminescence spectra between 400 and 500 nm were observed under 380 nm light excitation. The mechanism of the blue shift of the as-received samples in comparison with the reported boron carbide nanostructured materials is discussed.

The ferroelectric properties of hafnium oxide films are strongly influenced by the crystallization process due to the interaction of thermodynamics, kinetics, and mechanical stress. In this work, the influence of annealing temperature on the crystallographic properties and microstructure of Si-doped hafnium oxide thin films as well as their ferroelectric properties are investigated by X-ray diffraction, transmission Kikuchi diffraction, and electrical characterization. The findings reveal the emergence of a [100] and [110] out-of-plane texture for metal-ferroelectric-metal (MFM) and metal-ferroelectric-insulator-semiconductor (MFIS) capacitor structures with increasing annealing temperature, respectively. In combination with observed stress relaxation at higher temperatures and the evolution of the wake-up behavior, insights into the crystallization process and the influence of the interplay of microstructure and stress on the ferroelectric properties of hafnium oxide thin films are given.

Multilayered Si-doped DLC film with thicknesses of 5.5, 10.1, 21.8 and 28.3 μm was deposited on stainless steel, aluminum alloy and copper alloy substrates by plasma-enhanced chemical vapor deposition. The mechanical and tribological properties of multilayered Si-doped DLC films deposited on three different substrates were evaluated in this study. The hardness of the multilayered Si-doped DLC film of different substrates is related to the substrate material and internal stress. In a scratch test, the adhesion of the multilayered Si-doped DLC film increased with the film thickness. The multilayered Si-doped DLC film with a thickness of 28.3 μm on stainless steel substrate has the highest adhesion of 31 N. The adhesion of the multilayered Si-doped DLC film with different thicknesses on the copper alloy is relatively poor. The ball-on-disk friction test results show that the multilayered Si-doped DLC film with thicknesses of 5.5 and 10.1 μm is prone to shear deformation and exhibit high friction coefficient. The uneven stress distribution and surface deformation of the multilayered Si-doped film deposited on the aluminum alloy and the copper alloy cause the fluctuation and rise of the friction coefficient. The wear resistance of multilayered Si-doped DLC films on different substrates is related to stress shielding and adhesion strength.

Black Ni/Si-doped TiO2 nanostructures were successfully fabricated through electrochemical anodization of Ti–1Ni–5Si alloy and Sn-reduction treatment. After Sn-reduction treatment, the band gap of Ni/Si-doped TiO2 became much smaller compared to other samples, which can be attributed to the synergetic effect of Ni/Si doping and the large quantity of Ti3+/oxygen vacancy species induced by Sn-reduction treatment. The black Ni/Si-doped TiO2 nanostructures exhibited a remarkable enhancement in the photoelectrochemical (PEC) water splitting in comparison with the pure TiO2 and Ni/Si-doped TiO2. The highest photocurrent reached 2.15 mA/cm2 (at 0 V versus Ag/AgCl), corresponding to a conversion efficiency (~1.10%) which was 5.8 times that of the pure TiO2 nanotubes. The first-principles calculations using density-functional theory (DFT) showed that ion doping and self-doped Ti3+ defect levels in the forbidden gap induced through Sn-reduction treatment could improve the mobility of photogenerated carriers and suppress charge recombination, which was in well agreement with the experimental results.

The properties of water molecules in nano-confined geometries have significant roles in different fields such as adsorption, electrochemistry, biology, earth science, materials science, and nanoflu...

The DFT wB97XD/6-31G* method was used to calculate Si-doped single-walled carbon nanotubes of various diameters, SiC119 (NT-1) and SiC83 (NT-2). The oxygen adsorption on the silicon atom and the oxygen reduction reaction by attaching a proton with further reduction at the cathode were studied as a part of a two- and four-electron mechanism of the oxygen reduction reaction. The diagrams of free energy in an acidic and alkaline medium were constructed.

Adsorption properties of letrozole onto pure, Ge- and Si-doped C60 fullerene in different states were calculated using density functional theory calculations using the B3PW91 method and 6-311G(d, p) standard basis set in gas and solution phase. Our results indicated physisorption interaction in letrozole/C60. To achieve better results, letrozole was adsorbed onto Ge- and Si-doped C60 in four different states. However, sensitivity can be increased in the presence of Ge and Si doping, but Si doping indicated strong adsorption. Calculation in the solution phase (water as solvent) revealed a significant increase in the adsorption energy. It is predicted that letrozole incorporating Si-doped C60 can be extended as a drug delivery system.

In order to probe the band gap engineering to tune optical properties in YAuPb1-xSix (x = 0, 0.25, 0.50, 0.75 and 1) alloys, we used all electron full-potential linearized augmented plane wave (FP-LAPW+lo) method within the frame work of the density functional theory. The optimized structural parameters were in good agreement with other theoretical and experimental results. The calculated results of elastic constant satisfy the condition for mechanical stability at each composition for cubic symmetry. In addition, the study of elastic parameters are summarized for the calculation bulk modulus, Young’s modulus, shear modulus, Kleinman parameters, Poisson’s ratio and Lame’s co-efficient. To predict the brittle (ductile) nature of this composition, the Cauchy pressure, Poisson’s ratio and B/G ratio were also calculated. Using modified Becke and Johnson GGA, the band gap values of each composition were computed precisely. Further, it was observed that for 0.25 < x < 0.75, band gap structure revealed a direct band gap configuration. In order to analyze the electronic structure of each composition, the total and partial densities of states have been investigated in detail. Furthermore, the investigation of optical parameters in terms of dielectric functions revealed the potential of these alloys for optoelectronic devices.

We report the straightforward synthesis of Si-containing PAHs. The impact of pi-extension and exocyclic modifications on both the optical and redox properties is investigated using a joint experimental/theoretical approach. By taking advantage of the solid-state luminescence of these derivatives, electroluminescent devices are prepared. Such preliminary optoelectronic results highlight that these heteroatom-containing PAHs are promising building blocks for organic electronics.

The recent demand for analogue devices for neuromorphic applications requires modulation of multiple nonvolatile states. Ferroelectricity with multiple polarization states enables neuromorphic appl...

In this work, we studied the effect of a heteroatom (nitrogen and silicon) inside the main skeleton of the carbonaceous surface in the H chemisorption reaction. The process taking place on to an N-doped polycyclic aromatic hydrocarbon (PAH), known as PANHs, shows differences in the energetic parameters only when the process is carried out on to the N atom. When N is located in an external site of the surface, the process is barrierless, whereas if N is in an internal position of the surface the activation energy drastically increases. The aromaticity of these N-doped systems does not change much concerning pristine coronene. In a Si-doped PAHs, the chemisorption on to the Si atom takes place in the absence of activation energy, regardless the position of Si on the surface. Moreover, the adsorption on to their neighbour carbon atoms is carried out with lower activation energies than those found in the reaction on to pristine PAH, indicating that the presence of silicon atoms in the surface favours H chemisorption. This might be due to a loss of aromaticity on the surface. In both cases, the reactions become significantly more exoenergetic. Finally, the presence of heteroatoms favours kinetically the reaction, where the rate coefficient of H2 formation process, calculated considering all of the sites of every PAH studied in this work, reaches a close value to the reported for diffuse interstellar medium and photodissociation regions ($R_{_{\mathrm{ H}\mathrm{ }_2}} = 1 \times 10^{-17}$ cm3 s−1 at 40 K).

The far-infrared spectroscopy was used to analyze optical properties of PbTe single crystals doped with different amounts of Si. A dielectric function that takes into account the plasmon-phonon interaction was employed in the measured data manipulation. Two frequencies of plasmon-phonon coupled modes were obtained with the best-fit method, whereas the values for LO mode and plasma frequency (ωP) were calculated. The best-fit to the experimentally obtained spectra agrees very well with the theoretical prediction.

There is increasing demand for the ability to form ohmic contacts without lossy intermediate layers on both the top and bottom sides of metal-semiconductor-metal plasmoelectronic devices such as quantum cascade lasers and metasurface photodetectors. Although highly Si-doped n-GaAs surfaces can allow an ohmic contact without alloying, conditions for realizing nonalloyed ohmic contacts to other n-GaAs surfaces, originally buried inside but exposed by removing the substrate, have yet to be studied. We discovered that nonalloyed ohmic contacts to initially buried surfaces with a practically low contact resistivity down to 77 K can be realized by fulfilling certain requirements, specifically keeping the Si-doping concentration within a narrow range of 7.5 × 1018 to 1.25 × 1019 cm-3 and setting the growth temperature of the succeeding upper layers to a low value of 530 °C.

HfO2-based unconventional ferroelectric materials were recently discovered and have attracted a great deal of attention in both academia and industry. The growth of epitaxial Si-doped HfO2 films ha...

In this work, we have investigated the compensation effect of defects in lightly Si-doped GaN layer. It is found that the compensation of defects can be enhanced by increasing Si doping concentration and dislocation density in GaN layer. Subsequently, through theoretical analysis it is found that a more effective compensation is activated by increasing Si doping, which is mainly due to the enhanced effect of deep defects in the compensation role rather than by the increase of density of deep defects. Meanwhile, it is found that the yellow luminescence (YL) intensity of lightly Si-doped GaN samples increases with the increasing Si doping concentration, which can also be caused by the enhancement of compensation of deep level defects, while the increase of peak intensity of band edge luminescence with increasing Si doping is mainly caused by the increase of free carriers.

The ferroelectricity in ultrathin HfO2 offers a viable alternative to ferroelectric memory. A reliable switching behavior is required for commercial applications; however, many intriguing features of this material have not been resolved. Herein, we report an increase in the remnant polarization after electric field cycling, known as the “wake-up” effect, in terms of the change in the polarization-switching dynamics of a Si-doped HfO2 thin film. Compared with a pristine specimen, the Si-doped HfO2 thin film exhibited a partial increase in polarization after a finite number of ferroelectric switching behaviors. The polarization-switching behavior was analyzed using the nucleation-limited switching model characterized by a Lorentzian distribution of logarithmic domain-switching times. The polarization switching was simulated using the Monte Carlo method with respect to the effect of defects. Comparing the experimental results with the simulations revealed that the wake-up effect in the HfO2 thin film is acco...

In this investigation, the gamma photon shielding properties for the (Al:Si) and (Al + Na):Si dopped ISG glasses were investigated by using Photon Shielding and Dosimetry (Phy-X / PSD) software for the selected energy range. The obtained results showed that the highest MAC value belong to ISG-A00N glass. It was seen that the MAC values which were examined at all energies changed in harmony with WinXCom. Substituting an atomic fraction of (Al:Si) with (Al + Na):Si resulted in a reduction of the total atomic cross-section of the glass, which lowered the mass attenuation coefficient (MAC). In this study, computations were made for glasses with SiO2, Al2O3, B2O3, Na2O, CaO and ZrO2 content given with ISG-C, ISG-A00, ISG-A12, ISG-A22, ISG-A00N, ISG-A11N, ISG-A18N and ISG-A23N codes. MAC, LAC, HVL, TVL, Zeff, Neff, Ceff Zeq, EBF, EABF and FNRCS calculations were applied to assess the radiation protection parameters by using Phy-X/PSD software. In addition, MSP and PR values were calculated by using the SRIM code. In fact, each obtained parameter provides us very important information on radiation protection, and these methods are frequently used in the literature. ISG-A00N glasses were observed to have the highest attenuation coefficient. Thus, the MAC value gradually decreased as the Al, Na and Si contents increased. Likewise, the HVL, TVL and MFP values changed coherent with this. Moreover, Zeff and Neff values were seen in the ISG-A00N sample to take the maximum values to each other inversely. The most effective glass sample was seen as ISG-A00N glass at the mean free path penetration power of MSP and PR values. When all the results were evaluated, ISG-A00N glass which has the highest Si and Ca contents and density was found to be the glass with the best radiation shielding feature. It is also noteworthy that this glass does not contain any Al component. As the results of the investigation, it was found out that a very small doped of the Si increases the radiation shielding feature on the glass. It was seen that the ISG-A23N had the lowest ∑R value. The obtained results revealed that the ISG-A00N > ISG-A00 > ISG-C > ISG-A12 > ISG-A11N > ISG-A22 > ISG-A18N > ISG-A23N samples, in ascending order that attenuators for low energy radiations.

We performed spin-polarized density functional theory (DFT) to investigate the structural, electronic, and magnetic properties of silicon- (Si-) doped monolayer boron nitride (BN). The present study revealed that structural parameters like bond length, bond angle, and lattice parameters increase as Si-doped in the B site of monolayer BN. However, the bandgap of monolayer BN is reduced in the presence of the Si dopant. Moreover, the obtained magnetic moment and analysis of the total density of states (TDOS) show that Si-doped monolayer BN displays ferromagnetism. The calculated ferromagnetic transition temperature (Tc) value for Si concentration of 12.5% is 476 K which exceeds room temperature. The findings are avenues to enhance the application of monolayer BN for spintronics.

Producción Científica, Cathodoluminescence (CL) investigations are performed on nominally undoped and Si-doped ε-Ga2O3 samples grown by metal-organic vapor phase epitaxy on (0001)-Al2O3 substrates, using different carrier gases. All films exhibit a broad low-temperature CL emission extending over the photon energy range 2–3.4 eV. Emission deconvolution suggests that four narrower bands centered at about 2.4, 2.75, 3.0 and 3.15 eV may well account for the broad band. While the position of these peaks results independent of the growth conditions, significant intensity differences are observed. A general reduction of the broad emission is evidenced as the Si concentration increases. No band-to-band recombination is observed. Temperature dependence of the CL signal shows a trend consistent with radiative transitions from the CB to deep acceptor states, probably of intrinsic nature., Junta de Castilla y León (project VA283P18)

We report positron annihilation results on vacancy defects in Si-doped Al0.90Ga0.10N alloys grown by metalorganic vapor phase epitaxy. By combining room temperature and temperature-dependent Doppler broadening measurements, we identify negatively charged in-grown cation vacancies in the concentration range from below 1 x 10 16 cm(-3) to 2 x 10 18 cm(-3) in samples with a high C content, strongly correlated with the Si doping level in the samples ranging from 1 x 10 17 cm(-3) to 7 x 10 18 cm(-3). On the other hand, we find predominantly neutral cation vacancies with concentrations above 5 x 10 18 cm(-3) in samples with a low C content. The cation vacancies are important as compensating centers only in material with a high C content at high Si doping levels.

Here, we numerically prove that the severe polarization-induced electric field in the active region for [0001]-oriented InGaN-based green light-emitting diodes (LEDs) is reduced when heavily Si-doped GaN quantum barriers are adopted. However, the electron injection is accordingly sacrificed for the insufficient confinement capability of the p-type electron blocking layer (p-EBL). Hence, p-EBL structures with/without gradient AlN alloys are discussed to reduce the electron leakage, and the importance of the positive sheet polarization charges at the interface between the last quantum barrier (LQB) and the p-EBL on affecting the blocking barrier height for electrons is especially highlighted. Moreover, we also suggest utilizing specially designed p-AlGaN/p-GaN structure instead of p-GaN structure to serve as the p-type hole supplier, which is able to increase the kinetic energy of holes, thus assisting holes to overcome the energy band barrier height in p-EBL and increasing the hole concentration within the quantum wells.

The Haber-Bosch (HB) process combining nitrogen (N2) and hydrogen (H2) into ammonia (NH3) gas plays an essential role in the synthesis of fertilizers for food production and many other commodities. However, HB requires enormous energy resources (2% of world energy production), and the high pressures and temperatures make NH3 production facilities very expensive. Recent advances in improving HB catalysts have been incremental and slow. To accelerate the development of improved HB catalysts, we developed a hierarchical high-throughput catalyst screening (HHTCS) approach based on the recently developed complete reaction mechanism to identify non-transition-metal (NTM) elements from a total set of 18 candidates that can significantly improve the efficiency of the most active Fe surface, Fe-bcc(111), through surface and subsurface doping. Surprisingly, we found a very promising subsurface dopant, Si, that had not been identified or suggested previously, showing the importance of the subsurface Fe atoms in N2 reduction reactions. Then we derived the full reaction path of the HB process for the Si doped Fe-bcc(111) from QM simulations, which we combined with kinetic Monte Carlo (kMC) simulations to predict a ~13-fold increase in turnover frequency (TOF) under typical extreme HB conditions (200 atm reactant pressure and 500 °C) and a ~43-fold increase in TOF under ideal HB conditions (20 atm reactant pressure and 400 °C) for the Si-doped Fe catalyst, in comparison to pure Fe catalyst. Importantly, the Si-doped Fe catalyst can achieve the same TOF of pure Fe at 200 atm/500 °C under much milder conditions, e.g. at a much decreased reactant pressure of 20 atm at 500 °C, or alternatively at temperature and reactant pressure decreased to 400 °C and 60 atm, respectively. Production plants using the new catalysts that operate under such milder conditions could be much less expensive, allowing production at local sites needing fertilizer.

Density functional theory calculations are performed to probe reaction pathways of N2O reduction by CO molecule catalysed over Si-doped C3N (Si-C3N) nanosheets. According to our results, a single Si atom can be stabilised above the C- or N-vacancy site of C3N due to the formation of strong Si-N or Si-C covalent bonds. The reduction of N2O over Si-C3N is characterised as a two-step process. First, N2O is dissociated to N2 and an activated oxygen atom (Oads) without an energy barrier. Then, the Oads moiety is removed by CO molecule by overcoming negligible activation energy.

In this study, electron traps in dilute GaAsN are investigated using the temperature dependence of electron concentration (n) and mobility (μe) for annealed heavily Si-doped GaAsN. The temperature dependence of n and μe depends on the annealing temperature, indicating that electrons are excited to the conduction band only from deep electron traps for heavily Si-doped GaAsN annealed at 580 °C. However, they are excited to the conduction band from both the deep electron traps and the shallow Si donor level for heavily Si-doped GaAsN annealed at 550 °C. The depth of the deep electron traps from the bottom of the conduction band for heavily Si-doped GaAsN annealed at 550 °C is almost equal to heavily Si-doped GaAsN annealed at 580 °C. The results demonstrate that these deep electron traps are inherent in dilute GaAsN because similar deep electron traps are also observed for the as-grown Si-doped GaAsN.

This work describes results concerning the corrosion behaviour of Li, Na and Si doped eutectic Zn-Al alloys. Corrosion properties were investigated with the use of several complementary electrochemical techniques: time resolved OCP analysis, potentiodynamic studies, rotating disc electrode (RDE) and electrochemical impedance spectroscopy (EIS). The corrosion potential (Ecorr) and corrosion current (icorr) were obtained using potentiodynamic tests. The corrosion studies revealed that the alloying addition to eutectic Zn-Al resulted in slightly lower corrosion resistance than observed for Zn-Al. The results indicate that the addition of Si reduced corrosion resistance the least, compared to Li and Na.

Department of Science and Technology (HVD5S1X) and Council of Scientific and Industrial Research (CSIR).

Er2O3:ZnO layers were deposited on SiO2/Si substrates by conventional magnetron sputtering under room temperature(RT), the Si doped Er: ZnO films were achieved by direct Si implantation with various Si doses(ranging from 4 *1015 to 2.5 *1016 cm−2) and post annealing at two different temperatures 950 and 1200 °C. Surface morphological and structure properties were measured by optical microscope, x-ray diffraction (XRD) and transmission electron microscope (TEM). The Er-Si-O compounds were obtained in Si doped Er: ZnO sample after annealed at 1200 °C. An increased photoluminescence (PL) intensity and widened profile are attributed to the change of local surrounding of Er caused by modification of ZnO lattice and the formation of Er-Si-O compounds.

We report on a chemiluminescence (CL) system based on simultaneous enhancing effect of Si-doped carbon dots (Si-CDs) and cetyltrimethylammonium bromide (CTAB) on HCO3−-H2O2 reaction. The possible CL mechanism is investigated and discussed. Excited-state Si-CDs was found to be the final emitting species, which are probably produced via electron and hole injection by oxy-radicals. The effect of several other heteroatom-doped CDs and undoped CDs was also investigated and compared with Si-CDs. Furthermore, it was found that catecholamines such as dopamine, adrenaline and noradrenaline remarkably diminish the CL intensity of Si-CD-HCO3−-H2O2-CTAB system. By taking advantage of this fact, a sensitive probe was designed for determination of dopamine, adrenaline and noradrenaline with a limit of detection of 0.07, 0.60 and 0.01 μM, respectively. The method was applied to the determination of catecholamines in human plasma samples.

The specific contact resistance of golden contacts made by electroplating or evaporation for p-type InAs:Be and n-type InAs:Si epitaxial layers grown by MBE was studied. The Circular Transmission Line Model (CTLM) was applied to determine the specific contact resistance. The measured specific contact resistances were correlated with metallization method and Hall concentration of holes and electrons. The lowest resistances were obtained for highly Be and Si doped layers. It was shown that high quality low resistance contacts can be obtained by gold electroplating, especially for highly Be and Si doped InAs layers.

The electrical properties and photoluminescence features of uniformly Si-doped GaAs layers grown on GaAs substrates with the (100) and (111)A crystallographic orientations of the surface are studied. The samples are grown at the same As4 pressure in the growth temperature range from 350 to 510°C. The samples grown on GaAs(100) substrates possess n-type conductivity in the entire growth temperature range, and the samples grown on GaAs(111)A substrates possess p-type conductivity in the growth temperature range from 430 to 510°C. The photoluminescence spectra of the samples exhibit an edge band and an impurity band. The edge photoluminescence band corresponds to the photoluminescence of degenerate GaAs with n- and p-type conductivity. The impurity photoluminescence band for samples on GaAs(100) substrates in the range 1.30–1.45 eV is attributed to VAs defects and SiAs–VAs defect complexes, whose concentration varies with sample growth temperature. Transformation of the impurity photoluminescence spectra of the samples on GaAs(111)A substrates is interpreted as being a result of changes in the VAs and VGa defect concentrations under variations in the growth temperature of the samples.

Tuning the ion release ability of bioactive materials is one of the key factors for bone repair and regeneration. Calcium (Ca2+), magnesium (Mg2+), and silicate ions were reported to enhance the activity of bone-forming cells. In this work, the dissolution behavior of magnesium- and silicate-doped calcium carbonate (vaterite), denoted as MgSiV, embedded in three kinds of biodegradable polymers in Tris buffer solutions (TBS) were examined to find an effective ion releasing system. Poly(L-lactic acid) (PLLA) and poly(D,L-lactide-co-glycolide) (PDLLG, lactide:glycolide = 75:25 or 50:50; denoted as PDLLG75 and PDLLG50, respectively) were chosen as the matrix polymers. The Mg2+ and silicate ions were released rapidly within 3 d of soaking. Continuous release of Ca2+ ions from the composites induced the formation of aragonite on the film surfaces in the presence of Mg2+ ions. The amount of ions released from the MgSiV-PLLA composite was lesser than those released from the PDLLG-based composites. The fast degradation of PDLLG50 induced a decrease in the pH of TBS. The MgSiV-PDLLG75 composite exhibited a rapid release of Mg2+ ions, a continuous release of Ca2+ ions, and a controlled release of silicate ions with no reduction in the pH of TBS. Such release phenomena are caused by the formation of pathways for ion release, originating from the water uptake ability of PDLLG75.

Doping of Ga(Al)N layers by plasma-assisted molecular beam epitaxy in Ga-rich conditions on c-plane bulk GaN substrates was studied. Ga(Al)N samples, doped with Mg or Si, grown using different growth conditions were compared. In contrast to Si doped layers, no change in the Mg concentration was observed for layers grown using different growth rates for a constant Mg flux and constant growth temperature. This effect enables the growth of Ga(Al)N:Mg layers at higher growth rates, leading to shorter growth time and lower residual background doping, without the need of increasing Mg flux. Enhancement of Mg incorporation for Al containing layers was also observed. Change of Al content from 0% to 17% resulted in more than two times higher Mg concentration.

Black Si-doped TiO2 (Ti–Si–O) nanotubes were fabricated through Zn metal reduction of the Ti–Si–O nanotubes on Ti–Si alloy in an argon atmosphere. The nanotubes were used as a photoanode for photoelectrochemical (PEC) water splitting. Both Si element and Ti3+/oxygen vacancies were introduced into the black Ti–Si–O nanotubes, which improved optical absorption and facilitated the separation of the photogenerated electron–hole pairs. The photoconversion efficiency could reach 1.22%, which was 7.18 times the efficiency of undoped TiO2. It demonstrated that a Si element and Ti3+/oxygen vacancy co-doping strategy could offer an effective method for fabricating a high-performance TiO2-based nanostructure photoanode for improving PEC water splitting.

We studied Si-doped Ga2O3 photodetectors with a metal-semiconductor-metal structure that were fabricated using pulsed laser deposition and a post-annealing process under an oxygen atmosphere in a temperature range from 500 °C to 800 °C. After post-annealing, the Si-doped Ga2O3 photodetectors with 500 °C was showed the highest photoresponsivity (0.34 A/W) and external quantum efficiency (166.23%), while the device with 800 °C was exhibited the fastest switching speeds (0.88 s/0.18 s) for the on/off switching. These results are due to changes in the defect densities from the chemical bond formation between Si and O atoms. Our results show that post thermal annealing of Si-doped β-Ga2O3 layers can modify the photodetector performance depending on applications for high photoresponsivity or fast response time.

The influence of resistivity for n-AlGaN is investigated by changing Si concentration, growth temperature and growth rate. It is found that the resistivity strongly depended on the growth conditions and it reaches to a small value of 5 × 10−3 Ω cm at the growth temperature of 1040 °C. In addition, it is found that there is a strong correlation between the resistivity and the PL emission intensity of group-III-vacancy–Si (VIII-Si) complexes. It indicates that defect compensation can play a key role in high resistivity of n-AlGaN films.

Electron trapping in ferroelectric and non-ferroelectric HfO2-based layers was studied at room temperature by charge injection and photodepopulation techniques. The comparison of inferred energy distribution and density of trapped electrons in differently processed samples shows insignificant impact of Al- and Si-doping on trapping properties suggesting intrinsic nature of the observed traps. A comparison to the HfZrO4 layers is provided. The volume concentration of deep traps, most of which are energetically distributed between 2 and 3.5 eV below the HfO2 conduction band, is found to be in the range of 1019 cm−3.

With toluene soluble fraction of coal tar pitch, polycarbosilane and pyridine borane as raw materials, the modification coal tar pitch was synthesized by a liquid method. The B-Si-doped carbon materials were obtained by carbonization treatment at 800–1,600 °C for 1 h. The effects of carbonization temperatures on the composition, microstructure and oxidation resistance of the B-Si-doped carbon materials were investigated by XRD, SEM and TG-DSC. The results showed that the B-Si-doped carbon materials were composed of B2O3 and carbon. SiC crystal grains appeared when the carbonization temperatures were over 1,200 °C. The higher the carbonization temperatures were, the larger the SiC grain sizes of B-Si-doped carbon materials became. But oxidation rate of larger grain sizes of SiC was slow during oxidation. It was difficult to form a protective glassy film on the surface of the materials rapidly. Therefore, the B-Si-doped carbon materials obtained by carbonization at 1,200 °C showed better oxidation resistance. Oxidation resistance mechanism of B-Si-doped carbon materials was illustrated. The SiO2 produced by the oxidation of SiC and B2O3 formed protective glassy film, which had self-healing and anti-oxidation synergism.

In this paper, we present experimental results of photoluminescence for series of InAs:Si heavily doped samples, with doping level varying from 1.6 × 1016 cm-3 to 2.93 × 1018 cm-3. All samples were grown using MBE system equipped with a valved arsenic cracker. The measurements were performed in the temperature range of 20 K to 100 K. Although the Mott transition in InAs appears for electron concentrations above 1014 cm-3, Burstein-Moss broadening of photoluminescence spectra presented in this article was observed only for samples with concentration higher than 2 × 1017 cm-3. For the samples with lower concentrations two peaks were observed, arising from the band gap and defect states. The intensity of the defect peak was found to be decreasing with increasing temperature as well as increasing concentration, up to the point of disappearance when the Burstein-Moss broadening was visible.

Interactions of a bioactive propargylamine-based sulfonamide with the pristine, Al, and Si doped boron nitride nanotubes (BNNT) were studied using density functional theory calculations. The relative reactivity of the studied nanotubes toward the sulfonamide-based compound was as: Al-doped ≫ Si-doped > pristine BNNTs. It was found that there is a weak interaction between the sulfonamide and the pristine BNNT with adsorption energy of about −3.1 kcal/mol; therefore for this complex any change in the electronic properties is not expected. The sulfonamide adsorbed preferably on the Al and Si dopants from an oxygen atom of SO 2 group with adsorption energies of about −28.8 and −14.9 kcal/mol, respectively. Despite the highest reactivity of the Al-doped BNNT, its electronic properties were not sensitive to the sulfonamide. The results showed that after adsorption of the sulfonamide on the Si-doped BNNT, the electrical conductivity of BNNT significantly increases. Therefore, the Si-doped BNNT can be a potential candidate for detection of sulfonamide-based drugs. It was predicted that this sensor benefits a short recovery time of about 72 ms.