Using TCAD simulations, the silicon carbide metal-oxide-semiconductor field-effect transistor with p-type floating islands (SiC FLIMOSFET) is systematically investigated in this paper. The doping concentration (N _FLI ), length (L), and position (D1) of floating islands are optimized according to breakdown voltage (BV), electric field distribution, and on-resistance. The results show that NFLI = 1 × 10 ¹⁷ cm ^-3 , L = 2.5 μm, and D1 = 9.0 μm are superior values for FLI structure considering tradeoff between BV and on-resistance. With the same BV capacity, the on-resistance of SiC FLIMOSFET is decrease by 32% comparing to the conventional SiC VDMOSFET. Besides, the dynamic property shows 16.5% reduction of FoM R _{on} cdot Q _GD in the SiC FLIMOSFET. Significantly, comparing to the conventional structure, the electro-thermal simulation indicates that the SiC FLIMOSFET has a higher robustness under short-circuit condition owing to the reduction of thermal stress in SiC/SiO ₂ interface. All the results show that the SiC FLIMOSFET has a good potential in SiC power device.

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SnS monolayer has sparked intensive attention due to its unique electronic and optical properties. We systemically investigate the electronic properties of SnS by first-principles calculation. Our results show that the monolayer possesses indirect bandgap. We further perform mechanical strain to adjust the electronic structure of SnS, corresponding results display an indirect-direct transition of band gap when subjected to proper external strain. Interestingly, the bandgap can be linearly increase under tensile strain from 0% to 7%, while the bandgap reduced under compressive strain. For biaxial strain, the band gap changes more remarkable compared with that under uniaxial strain (zigzag x or armchair y direction). Furthermore, we demonstrate that the gas molecules (CO₂, H₂S, C₂H₄ and NO₂) adsorption property on SnS monolayer can be modulated through biaxial strain. Especially, the NO₂ adsorption is further enhanced on the SnS monolayer under biaxial tensile strain. These results may provide guidance for fabricating SnS-based strained gas sensor.

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IGBT device is developed from silicon to wide bandgap semiconductor materials, and its working temperature has reached to 300 °C, so the encapsulation is particularly important. NanoCu paste is investigated under H2 at 300°C. A chip is linked to DBC substrate by nanoCu paste under air with different temperature. Results shows the increase of sintered time temperature effectively reduce the porosity of sintered layer and enhance the strength.

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Sensitive materials for formaldehyde (HCHO) sensor need high sensitivity and selectivity. The research on two dimensional (2D) sensitive material is growing, and most studies focus on the pristine or modified graphene. So it is essential to introduce other 2D materials into HCHO gas sensor. In this report, the adsorption behaviors of organic gas molecules including C₂H₆, C₂H₄, C₂H₂, C₆H₆, C₂H₅OH and HCHO over indium triphosphide (InP₃) monolayer were studied by using first-principle atomistic simulations. The calculation results demonstrate that InP₃ monolayer has a high sensitivity and selectivity to HCHO than others. By comparing the structures and adsorption results of InP₃ monolayer, graphene and single-layered MoS₂, it was found that the polarity bonds and steric effect of the site on monolayer play an important role in the detection of HCHO. The effect of strain on the gas/substrate adsorption systems was also studied, implying that the stained InP₃ monolayer could enhance the sensitivity and selectivity to HCHO. This study provides useful insights into the gas-surface interaction that may assist future experimental development of 2D material for HCHO sensing and performance optimization based on strain.

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The sensing behavior of monolayer tin sulfide (SnS) for four gas molecules (NH₃, NO₂, CO, and H₂O) are studied by the first-principle calculation based on density-functional theory. We calculate adsorption energy, adsorption distance, and Hirshfeld charge to estimate the adsorption ability of monolayer SnS for these gas molecules. The results demonstrate that all the gas molecules show physisorption nature. We further calculate the current-voltage (I -V ) curves using the nonequilibrium Green's function formalism for evaluating the NO₂ gas sensing properties. The monolayer SnS is found to be strongly sensitive to NO₂ molecule dependent on moderate adsorption energy, excellent charge transfer, and significant change of I -V property before and after gas adsorption. Therefore, we suggest that monolayer SnS can be a prominent candidate for application as NO₂ gas sensor.

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We proposed a molecular modeling methodology to study the protonic acid doping of emeraldine base polyaniline which can be used in gas detection. The commerical forcefield COMPASS was used for the polymer and protonic acid molecules. The molecular model, which is capable of representing the polyaniline doping with the aqueous hydrochloric acid, was built by Monte Carlo method. The initial entire systems were equilibrated using a new protocol, which aims at creating a final structure with realistic density and low-potential energy characteristics. The doping process is modeled by a combined molecular mechanics and molecular dynamics simulation technique. The radial distribution functions of doped emeraldine salt and the relationships including pKa/pH and doping percentage/pH, were computed and compared with the experimental data. This method contributes a novel molecular modeling approach to select and evaluate the conducting polymers in chemical sensor applications.@en

We presented a molecular model to investigate the relationship between macroscopic conductivity and charge carrier density in polyaniline (PANI) as chemical sensing materials. It was demonstrated that the conductivity in polyaniline depends on the charge carrier density. The charge carrier density dependence behavior of the conductivity was described as an exponential function ¿ = (An)a. The predicted relationship was verified by the previous study on the charge carrier density dependence of the mobility from the other research group. Using the computing relationship of conductivity/charge carrier density, the sensitivity of emeraldine base polyaniline (EB-PANI) and its derivative, potassium sulfonated polyaniline (K-SPANI) for the detection of HCl was evaluated. It was clearly seen that the sensitivity of K-SPANI was greatly improved about 2 orders of magnitude compared to EB-PANI. This simulation result was verified by the literature reported experimental results. The computational methodology used in this research can be used for determining the sensing properties in design and evaluation of chemical sensing materials.@en

Gas sensors fabricated with nanowires as the detecting elements are powerful due to their many improved characteristics such as high surface-to-volume ratios, ultrasensitivity, higher selectivity, low power consumption, and fast response. This paper gives an overview on the recent process of the development of nanotechnology and nanowire-based gas sensors. The two basic approaches, top-down and bottom-up, for synthesizing nanowires are compared. The conduction mechanisms, sensing performances, configurations, and sensing principles of different nanowire gas sensors and arrays are summarized and discussed. Meanwhile, an emerging nanowires fabrication method and a self-powered nanowire pH sensor are highlighted. The scientific and technological challenges in the field are discussed at the end of the review.@en

We report a molecular modelling study to validate the forcefields [condensed-phase optimised molecular potentials for atomistic simulation studies (COMPASS) and polymer-consistent forcefield (PCFF)] in predicting the physical and thermophysical properties of polymers. This work comprises of two key steps: (1) generating and validating the molecular model in predicting the material properties of the bulk amorphous emeraldine base polyaniline and (2) modelling the glass-rubber transition of the polymer. From all the molecular dynamics simulation results, it clearly shows that the more recent COMPASS forcefield provides a higher accuracy in predicting the polymer properties than PCFF and it enables a more accurate prediction of condensed-phase properties (density, glass transition temperature, solubility parameters, etc.) in a broad range of temperature for various applications.@en

We report a molecular modeling study to evaluate and select conducting polymers (CPs) for use as the sensing layer for carbon dioxide (CO2) sensor. The interactions between gases and sensing materials and the adsorptions of small gas molecules on polymer sensing films are described and investigated. Polymers considered for this work include emeraldine base polyaniline (EB-PANI) and unprotonated sodium polyaniline salt (NaSPANI) with sulfur to nitrogen ration (S/N) of 0.4, 0.5 and 0.6 Gases studied include CO2, humidity (H2O). Comparative studies of NaSPANI and PANI show differences on the polymer-gas interaction energy and gas sorption number because of the -So3NA groups on the phenyl rings.@en

We present a molecular modeling methodology to investigate the effect of functional group on the working range of polyaniline sensors for carbon dioxide (CO2) in agriculture industry. Doping plays the key role in the sensing mechanism of conducting polymer sensors. The adsorption of CO2 and water, which governs the production of protons and polymer solubility in water, is important for doping and thus a key property for gas sensing. The molecular model, which is capable of studying the interaction among the functionalized polyaniline, CO2 gas and water solvent, is employed to study the adsorption. The loading number of adsorbates in the polymer systems at the fixed temperature and pressure is calculated. Combined with previously reported experimental data, the predicted working range of the NaSPANI is [102,104] ppm. It indicates that NaSPANI can be used for agricultural CO2 detection. This method is a useful design tool for evaluating novel sensing materials. Keywords Molecular modeling; Conducting polymers; Polyaniline; Carbon dioxide sensors; Working range --------------------------------------------------------------------------------@en

Molecular dynamics (MD) and molecular mechanical (MM) analysis are carried out to provide reliable and accurate model for emeraldine base polyaniline. This study validate the forcefields and model with the physical and mechanical properties of the polyaniline. The temperature effects on non-bond energy, potential energy and solubility parameter during the transformation from the rubbery to the glassy state have been analysed in this work. A new method using the solubility versus temperature (delta-T) curve for predicting the Tg of polymer are suggested. Keywords: Emeraldine base; molecular dynamics; forcefields; glass transition.@en