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Effect of Post Oxide Annealing on the Electrical and Interface 4H-SiC/Al<sub>2</sub>O<sub>3</sub> MOS Capacitors
摘要： This paper reports on the effect of forming gas annealing on the C-V characteristics and stability of Al2O3/SiC MOS capacitors deposited by atomic layer deposition, (ALD). C-V and I-V measurements were performed to assess the quality of the Al2O3 layer and the Al2O3/SiC interface. In comparison to as-deposited sample, the post oxide annealing (POA) in forming gas at high temperatures has improved the stability of C-V characteristic and the properties at the interface of Al2O3/SiC capacitors. However, the oxide capacitance and oxide breakdown electric field degrade with increased annealing temperature. The results provide indications to improve the performance of Al2O3/SiC capacitors 4H-SiC devices by optimizing the annealing temperature.
关键词： forming gas,Al2O3,atomic layer deposition,interface state density,4H-SiC
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - High-performance carbon nanotube paste emitters by using the optimal size distribution of SiC nanometer-fillers aggregates
摘要： We improved carbon nanotube (CNT) paste field emitter by optimizing the size distribution of SiC aggregates as inorganic fillers using a novel milling process. The average size of SiC aggregates was reduced to sub-micrometer with a relatively narrow distribution. The CNT paste emitter with the optimized small SiC fillers of 1 μm in D50, by the milling process, exhibited better adhesive property and more uniform surface morphology than that with large fillers from the as-purchased SiC. Furthermore, the optimized small fillers shows superior field emission performance even under a high current density, making the CNT paste technology very useful for a variety of field emission devices.
关键词： milling process,Field emission,Carbon nanotube (CNT),paste formulation,SiC
更新于2025-09-23 15:21:21
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Analog and RF assessment of sub-20?nm 4H-SiC trench gate MOSFET for high frequency applications
摘要： In this work, 4H-SiC Trench Gate (Recessed Channel) (4H-SiC-RC) MOSFET structure is demonstrated to have superior analog and RF Figure of Merits (FOMs) by numerical simulation. The integration of 4H-SiC with phosphorene contact on to the trench region results in higher drain current (2.3 mA) and outstanding switching ratio (1016) owing to reduced off-current which leads to the lower sub-threshold slope (SS). Other electrical parameters such as electric ?eld, electron mobility, and electron velocity are remarkably improved in 4H-SiC-RC MOSFET. Further, the high-frequency RF FOMs have also been studied, and it is observed that cut-off frequency (fT) gets doubled and maximum oscillator frequency (fMAX) increased by ?ve times in the proposed design as compared to conventional design. Thus, the 4H-SiC-RC design is suitable for high switching, high power, and high-frequency application.
关键词： Gain,RF,4H-SiC-RC-MOSFET,Stray capacitance,Analog,Frequency
更新于2025-09-23 15:21:21
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Microwave dielectric properties of B and N co-doped SiC nanopowders prepared by combustion synthesis
摘要： B and N co-doped SiC nanopowders were prepared by combustion synthesis under a nitrogen atmosphere from the Si/C system, using α-Si3N4 powder and B powder as solid nitriding agent and dopant, respectively. The prepared particles had spherical morphology and narrow size distribution. XPS analysis demonstrated that B and N atoms successfully incorporated into SiC crystal and formed Si1-xBxC1-yNy solid solution. Results of dielectric properties showed that the real part ε′ and imaginary part ε″ of the complex permittivities of the samples decreased first, and then increased with increasing N content. The sample with 5% B and 15% N revealed the greatest values in ε′ and ε″ and better microwave absorption performance. The corresponding mechanism of the dielectric properties of SiC improved by co-doping was discussed in detail.
关键词： co-doping,SiC,dielectric property,microwave loss
更新于2025-09-23 15:21:21
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Influence of 4H-SiC substrate miscut on the epitaxy and microstructure of AlGaN/GaN heterostructures
摘要： AlGaN/GaN heterostructures were grown on “on-axis” and 2° off (0001) 4H-SiC substrates by metalorganic vapor phase epitaxy (MOVPE). Structural characterization was performed by transmission electron microscopy. The dislocation density, being greater in the on-axis case, is gradually reduced in the GaN layer and is forming dislocation loops in the lower region. Steps aligned along [11?00] in the off-axis case give rise to simultaneous defect formation. In the on-axis case, an almost zero density of steps is observed, with the main origin of defects probably being the orientation mismatch at the grain boundaries between the small not fully coalesced AlN grains. V-shaped formations are observed in the AlN nucleation layer, but are more frequent in the off-axis case, probably enhanced by the presence of steps. These V-shaped formations are completely overgrown by the GaN layer, during the subsequent deposition, presenting AlGaN areas in the walls of the defect, indicating an inter-diffusion between the layers. Finally, at the AlGaN/GaN heterostructure surface in the on-axis case, V-shapes are observed, with the AlN spacer and AlGaN (21% Al) thickness on relaxed GaN exceeding the critical thickness for relaxation. On the other hand, no relaxation in the form of V-shape creation is observed in the off-axis case, probably due to the smaller AlGaN thickness (less than 21% Al). The AlN spacer layer, grown in between the heterostructure, presents a uniform thickness and clear interfaces.
关键词： TEM,HEMT,SiC substrate,Heterostructure,AlGaN/GaN,HRTEM
更新于2025-09-23 15:21:21
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Effective Photocatalytic Hydrogen Evolution by Cascadal Carrier Transfer in the Reverse Direction
摘要： Visible-light-responsive photocatalysts used in the highly efficient hydrogen production exhibit several disadvantages such as photocorrosion and fast recombination. Because of the potential important applications of such catalysts, it is crucial that a simple, effective solution is developed. In this respect, in this study, we combined SiC (β modification) and TiO2 with CdS to overcome the challenges of photocorrosion and fast recombination of CdS. Notably, we found that when irradiated with visible light, CdS was excited, and the excited electrons moved to the conduction band of TiO2, thereby increasing the efficiency of charge separation. In addition, by moving the holes generated on CdS to the valence band of SiC, in the opposite direction of TiO2, photocorrosion and fast recombination were prevented. As a result, in the sulfide solution, the CdS/SiC composite catalyst exhibited 4.3 times higher hydrogen generation ability than pure CdS. Moreover, this effect was enhanced with the addition of TiO2, giving 10.8 times higher hydrogen generation ability for the CdS/SiC/TiO2 catalyst. Notably, the most efficient catalyst, which was obtained by depositing Pt as a cocatalyst, exhibited 1.09 mmol g?1 h?1 hydrogen generation ability and an apparent quantum yield of 24.8%. Because water reduction proceeded on the TiO2 surface and oxidative sulfide decomposition proceeded on the SiC surface, the exposure of CdS to the solution was unnecessary, and X-ray photoelectron spectroscopy confirmed that photocorrosion was successfully suppressed. Thus, we believe that the effective composite photocatalyst construction method presented herein can also be applied to other visible-light-responsive powder photocatalysts having the same disadvantages as CdS, thereby improving the efficiency of such catalysts.
关键词： CdS,photocorrosion,hydrogen production,TiO2,photocatalysts,SiC,fast recombination
更新于2025-09-23 15:21:21
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Room temperature spin injection into SiC via Schottky barrier
摘要： Electrical spin injection into and spin extraction from a wide-bandgap semiconductor SiC at room temperature were demonstrated via Schottky junctions. The spin relaxation time of SiC could reach 300 ps, overwhelming that of Si with similar carrier density due to the smaller atomic number. We also found that there existed two channels in SiC/CoFeB Schottky junctions for spin relaxation, one from bulk SiC and the other from interfacial defect states within the barrier whose spin relaxation times were about 1 ns. The bias condition controlled transport channels via bulk or defect states within the barrier and then affected the effective spin relaxation process. Realization of spin injection into SiC shed light on spintronics of wide-bandgap semiconductors such as spin-resolved blue light emitting diodes and high power/temperature spintronics.
关键词： spintronics,SiC,spin injection,Schottky barrier,wide-bandgap semiconductor
更新于2025-09-23 15:21:21
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A study of deformation behavior and phase transformation in 4H-SiC during nanoindentation process via molecular dynamics simulation
摘要： The deformation behavior and phase transformation of 4H silicon carbide (4H-SiC) during nanoindentation process is investigated with a cube corner diamond indenter through molecular dynamics simulation. It is found through the research that the basal dislocations are most likely to be generated in (0001) face and the indentation process contributes to the distortion of 4H-SiC lattice. In addition, phase transformation from 4H-SiC to 3C-SiC is firstly observed via MD simulations during indentation process. Cross-sectional observation in (12 10) plain shows that 3C-SiC layers appear firstly during nanoindentation process, and the layers are observed at small indentation depth. 3C-SiC grain is generated based on 3C-SiC layers, and the transformation is more likely to appear at larger indentation depth. The phase transformation from 4H-SiC to 3C-SiC results from the shear stress induced by indenter during loading process. 3C-SiC grain and layers are both generated from the slip of 3C seeds under the influence of shear stress, and the condition of 3C-SiC grain formation is stricter. Moreover, the P-h curve is studied and the vertical deformation mode during indentation process on 4H-SiC can be reflected on P-h curve as small pop-in events. The findings are meaningful for the study of deformation mechanism of SiC and the application of SiC in precision machining.
关键词： molecular dynamics simulation,cube corner diamond indenter,3C-SiC grain,4H-SiC,phase transformation,3C-SiC layer
更新于2025-09-23 15:21:01
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[Ceramic Engineering and Science Proceedings] Proceeding of the 42nd International Conference on Advanced Ceramics and Composites (Ceramic Engineering and Science Proceedings Volume 39, Issue 2) || Influences of Laser Condition and Slit Shape on Joinability of Zircaloy-SiC/SiC Composite Tube Joint
摘要： As for the fuel cladding in the light-water reactor, silicon carbide fiber reinforced silicon carbide composite (SiC/SiC composite) is one of the promising candidates as a replacement of zircaloy due to many superiorities, where it is necessary to develop the end-cap seal of SiC/SiC composite cladding. In this research, the caulking method was employed as the method for sealing the end cap of SiC/SiC composite tube by zircaloy tube where the titanium micro-powder was inserted between two tubes. The diode or fiber laser was circumferentially irradiated on the outer surface of zircaloy tube, and the insert method of titanium powder was varied by changing the cutting method of SiC/SiC composite tube. The results using the diode laser irradiations with the screw cutting indicated that the wider width of irradiation line seems to be inadequate because the shrinkage of zircaloy would break the thread of SiC/SiC composite. In addition, the examinations about the slit shape effect for the flat cutting suggested that the hook slit is considered to be the best cutting method for holding the titanium powder during the laser irradiation where the width of slit should be narrower than that of laser irradiation line.
关键词： SiC/SiC composite,titanium micro-powder,caulking method,laser irradiation,zircaloy
更新于2025-09-23 15:21:01
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Impact of design and process variation on the fabrication of SiC diodes
摘要： We have studied the influence of design and process variations on the electrical performance of SiC Schottky diodes. On the design side, two design variations are used in the active cell of the diode (segment design and stripe design). In addition, there are two more design variations employed for the edge termination layout of the diodes, namely, field limiting ring (FLR) and junction termination extension (JTE). On the process side, some diodes have gone through an N2O annealing step. The segment design resulted in a lower forward voltage drop (VF) in the diodes and the FLR design turned out to be a better choice for blocking voltages, in the reverse bias. Also, N2O annealing has shown a detrimental effect on the diodes’ blocking performance, which have JTE as their termination design. It degrades the blocking capability of the diodes significantly.
关键词： JBS diode,IGBT,N2O annealing,hybrid SiC,SiC
更新于2025-09-23 15:21:01