A marigold-like SiC@MoS2 nanoflower with a unique Z-scheme structure efficiently achieves the overall conversion of gas phase CO2 with H2O (CO2 (g) + 2H2O (g) = CH4 + 2O2) without any sacrificial reagents under visible light (λ ≥ 420 nm) irradiation. The CH4 and O2 evolution are 323 and 621 μL·g-1·h-1, and stable throughout 5 cycle reactions of total 40 h. This work demonstrates a breakthrough in artificial photosynthesis with the Z-scheme 1D heterojunction constructed by combining 2D semiconductor and 3D semiconductor based on the transfer balance of photogenerated electron and hole.

Visible-Light Driven Overall Conversion of CO2 and H2O to CH4 and O2 on 3D-SiC@2D-MoS2 Heterostructure.

Simple analytical approximation has been obtained to describe the temperature and concentration dependencies of the low-field mobility in gallium nitride (GaN) in wide temperature (50⩽ T ⩽1000 K) and concentration (10 14 ⩽ N ⩽10 19 cm −3 ) ranges. The dependence of the temperature T m at which the mobility μ is at a maximum on the doping level is also obtained. Results obtained can be directly used for computer simulation of GaN-based devices.

Carrier mobility model for GaN

This paper presents a comprehensive short-circuit ruggedness evaluation and numerical investigation of up-to-date commercial silicon carbide (SiC) MOSFETs. The short-circuit capability of three types of commercial 1200-V SiC MOSFETs is tested under various conditions, with case temperatures from 25 to 200 °C and dc bus voltages from 400 to 750 V. It is found that the commercial SiC MOSFETs can withstand short-circuit current for only several microseconds with a dc bus voltage of 750 V and case temperature of 200 °C. The experimental short-circuit behaviors are compared, and analyzed through numerical thermal dynamic simulation. Specifically, an electrothermal model is built to estimate the device internal temperature distribution, considering the temperature-dependent thermal properties of SiC material. Based on the temperature information, a leakage current model is derived to calculate the main leakage current components (i.e., thermal, diffusion, and avalanche generation currents). Numerical results show that the short-circuit failure mechanisms of SiC MOSFETs can be thermal generation current induced thermal runaway or high-temperature-related gate oxide damage.

Temperature-Dependent Short-Circuit Capability of Silicon Carbide Power MOSFETs

The stoichiometric photocatalytic reaction of CO2 with H2O is one of the great challenges in photocatalysis. Here, we construct a Cu2O-Pt/SiC/IrOx composite by a controlled photodeposition and then an artificial photosynthetic system with Nafion membrane as diaphragm separating reduction and oxidation half-reactions. The artificial system exhibits excellent photocatalytic performance for CO2 reduction to HCOOH and H2O oxidation to O2 under visible light irradiation. The yields of HCOOH and O2 meet almost stoichiometric ratio and are as high as 896.7 and 440.7 μmol g−1 h−1, respectively. The high efficiencies of CO2 reduction and H2O oxidation in the artificial system are attributed to both the direct Z-scheme electronic structure of Cu2O-Pt/SiC/IrOx and the indirect Z-scheme spatially separated reduction and oxidation units, which greatly prolong lifetime of photogenerated electrons and holes and prevent the backward reaction of products. This work provides an effective and feasible strategy to increase the efficiency of artificial photosynthesis. The stoichiometric photoreaction of CO2 with H2O is one of the big challenges in photocatalysis. An artificial photosynthetic system based on a direct and indirect Z-scheme heterostructure is synthesised, enabling simultaneous CO2 reduction to HCOOH and H2O oxidation to O2.

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Direct and indirect Z-scheme heterostructure-coupled photosystem enabling cooperation of CO 2 reduction and H 2 O oxidation

The behavior of silicon carbide (SiC) power MOSFETs under stressful short-circuit (SC) conditions is investigated in this paper. Two different SC failure phenomena for SiC power MOSFETs are thoroughly reported. Experimental evidence and TCAD electrothermal simulations are exploited to describe and discriminate the failure sources. Physical causes are finally investigated and explained by means of properly calibrated numerical investigations and are reported along with their effects on devices’ SC capability.

/pdf/a-comprehensive-study-of-short-circuit-ruggedness-of-silicon-1isyxadvdu.pdf

A Comprehensive Study of Short-Circuit Ruggedness of Silicon Carbide Power MOSFETs

Simple analytical approximations are proposed for describing the temperature and concentration dependences of low-field mobility in the main polytypes of silicon carbide (SiC): 6H, 4H and 3C in wide ranges of temperature and concentration. The obtained results can be directly used for the computer simulation of SiC-based devices. Different approaches to the analytical approximation of SiC parameters are critically correlated and analysed.

http://iopscience.iop.org/article/10.1088/0268-1242/17/9/313/pdf

Carrier mobility model for simulation of SiC-based electronic devices

Experimental data on electron and hole mobility in three silicon carbide polytypes, 4H-SiC, 6H-SiC, and 3C-SiC, are analyzed. A semiempirical model is proposed for describing the dependence of the majority carrier mobility on temperature and doping level. The model describes well the accumulated body of experimental data and can be applied to model characteristics of multilayer silicon carbide structures.

Semiempirical Model of Carrier Mobility in Silicon Carbide for Analyzing Its Dependence on Temperature and Doping Level

A simple analytical method is suggested to calculate the mobility of majority carriers in semiconductors. The method allows one to adequately describe experimental data in a wide range of temperatures and doping levels in various kinds of semiconductors: elementary (Si), III-V (GaAs), IV-IV (various SiC polytypes), and III-N (GaN). The high accuracy of the results of the calculation suggests that the method is universal, and it may be used to calculate the mobility of majority carriers in other semiconductor materials. The simplicity and accuracy of the technique make it promising for computer simulations of multilayer semiconductor structures.

Universal Analytical Approximation of the Carrier Mobility in Semiconductors for a Wide Range of Temperatures and Doping Densities

The problem of expedient limitations on the blocking voltage of SiC rectifier diodes is considered, with a full set of nonlinear physical phenomena responsible for the energy loss in semiconductor structures taken into account. The physical nature of the limitations on the blocking voltage is analyzed. It is shown that Auger recombination is the most important physical effect that restricts the blocking capability of high-voltage SiC diodes. It is demonstrated that the advisability of using a single diode or several in-series-connected diodes depends on the W/L ratio (W is the base width, and L is the ambipolar diffusion length) and temperature. A method that can be used to determine the optimal parameters of SiC power diode structures is suggested.

https://iopscience.iop.org/article/10.1088/0268-1242/24/12/125010/pdf

L. I. Pomortseva

Papers

Carrier mobility model for simulation of SiC-based electronic devices

Semiempirical Model of Carrier Mobility in Silicon Carbide for Analyzing Its Dependence on Temperature and Doping Level

Universal Analytical Approximation of the Carrier Mobility in Semiconductors for a Wide Range of Temperatures and Doping Densities

Fundamental physical limitations on the blocking voltage of SiC rectifier diodes