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The reverse breakdown characteristics of 4H-SiC Junction Barrier Schottky (JBS) rectifiers adopting the different floating limiting rings (FLRs) termination structures are experimented and analyzed under the repetitive avalanche current stress. The experimental results indicate that the breakdown voltage (BV) shift of the device after the repetitive avalanche current stress is highly dependent on the FLRs design, which determines the distributions of the surface electric field and avalanche current at avalanche condition. It is proved that the uniform surface electric field distribution of the FLRs structure at avalanche condition is helpful for the device achieve to achieve better BV shift robustness on the repetitive avalanche current stress. Additionally, the FLRs structure, which has smaller S1 and enough Nr, can present both higher BV and excellent BV shift robustness on the repetitive avalanche current stress.

Over the years, stereolithography has been successfully used to prepare complex, strong silicon carbide (SiC) structures. However, most raw materials are dark in color and therefore have broad-spectrum absorbing properties, making the curing steps during stereolithography highly inefficient. Here, diamond powders were mixed with a light-curing resin, yielding a slurry with excellent curability. The slurry was then used to prepare SiC-based composites with complex morphologies using pyrolysis and reaction melt infiltration (RMI) process. The influence of the diamond volume fraction in the slurry on each process stage was investigated. The infiltration of molten Si into diamond body during RMI was greatly enhanced compared to traditional carbon bodies. SiC ceramic-based composites with complex morphologies and a maximum strength of ∼460 MPa was prepared rapidly and efficiently. This study demonstrates the great potential of the slurry for efficiently manufacturing SiC-based composites in mechanical parts where high strength and complex structures are needed.

Diamond/SiC composites with high thermal conductivity are important materials for electronic industry, especially electronic packaging, but their complex structures and high-precision manufacturing are still challenging issues. Stereolithography-based manufacturing method combined with the reactive melt infiltration to make diamond/SiC composites with high-precision complex structures has been proposed in this paper. Diamond particles were used as the raw material, and as the particle size is a key factor affecting composite performance its influence was studied by means of measuring parameters, examining microstructure, and detecting components, whereas related mechanisms are discussed as necessary. Subsequently, a diamond/SiC composite with the thermal conductivity of 245.68 W/(m K) has been prepared and used in experiment. The experiment shows that the precision is affected by light-scattering and bending in the printing plane and in the vertical plane respectively, with the size errors of 0.25 and 0.12 mm.

The properties of 4H–SiC/Ni/Ti/Al/W metal contacts on n-type and p-type ion-implanted 4H–SiC layers are studied in this paper, with the aim of realizing simultaneous ohmic contact formation. The thickness of the Al film and the alloying temperature are analyzed. Specific contact resistances of 8 × 10−4 Ω cm2 and 4.1 × 10−5 Ω cm2 were achieved with multi-metal layer Ni/Ti/Al/W (80/30/110/50 nm) for n-type and p-type 4H–SiC, respectively, at an annealing temperature of 750 °C. This is for first time at such a low annealing temperature that ohmic contacts have been reported to simultaneously form on n-type and p-type 4H–SiC with satisfactory specific contact resistances. Samples were characterized using AFM, XRD, AES and TEM, and the results indicate that the presence of the W top layer facilitates lowering the surface roughness and accumulating elemental Ni and Al on the SiC side during annealing, which benefits the formation of the ohmic contacts.

Zirconia ceramic is a widely used material for dental restoration. Stabilized zirconia all-ceramic teeth have excellent mechanical properties, biocompatibility, and aesthetic properties. At present, the CAD/CAM technique for zirconia all-ceramic dental prosthesis leads to low material efficiency and high tool wear. Although restorations fabricated using additive manufacturing are gaining attention, it is still very challenging to obtain accurate shapes and proper mechanical properties in zirconia restorations. In this investigation, a type of three-part auxiliary support was adopted and added to the occlusal surface to fabricate a typical molar crown bridge. A ceramic solid content of 40 vol% acrylic-based slurry was prepared, and a molar crown bridge was fabricated using mask projection stereolithography. The experimental results showed that the average dimensional error of the printed green body was ±150 μm. The density of the sintered ceramic parts was 6.026 g/cm3, and the three-point bending strength was 541 ± 160 MPa, which is higher than that of human dentin (160 MPa), but lower than that of CAD/CAM zirconia (900–1200 MPa). Although the proposed process still needs to be optimized to improve the mechanical properties and reliability of the crown bridge, the mask projection process combined with the adopted three-part auxiliary supports are capable of individualized manufacturing of complex zirconia crown bridges.

Ceramic mask projection stereolithography (CMSL) is an additive manufacturing (AM) technology which is capable of implementing delicate structural designs of ceramic parts. Studies have shown that soft-start exposure mode has an effect on the polymer properties of the cured resin, such as conversion degree, curing speed etc. However, the effect of soft-start exposure on CMSL process has not received much attention. In this investigation, soft-start exposure was compared with constant exposure. The results showed that the soft-start exposure reduced the critical exposure energy (maximum reduction of 48.2%) of the slurry. The feature dimensional error of soft-start exposure was smaller than constant exposure by 25–45%. The soft-start exposure also had an effect on the strength of sintered parts. The bending samples fabricated by soft-start exposure had higher Weibull moduli (maximum increase of 47.2%), indicating that soft-start exposure stabled the curing process.

In this study, the effects of high-energy proton radiation on the effectiveness of edge terminations using field limiting rings (FLRs) in 4H–SiC junction barrier Schottky (JBS) diodes were examined in detail. The devices were irradiated using 5-MeV protons at fluences ranging from 5× 1012 cm−2 to 5× 1014 cm−2. Further, the reverse breakdown performances of the investigated devices were measured both before and after irradiation. Proton irradiation initially decreased the breakdown voltage (BV); subsequently, the BV was increased as the proton fluence increased. At a fluence of 5× 1013 cm−2, the BV was reduced by approximately 18%, whereas it was reduced by approximately 5% at a higher proton fluence of 5× 1014 cm−2. The related degradation mechanism that was associated with this phenomenon was also investigated using the numerical simulations of the current-voltage ( I - V ) and capacitance-voltage ( C - V ) characteristics of the device. The main contribution to the radiation-induced changes in BV originates from the variations of charge distribution at the SiO2/4H–SiC interface and the reduction of the net carrier density in the drift region. Both the aforementioned variations affect the spread of the electric field in the FLR edge termination regions.

Mask projection stereolithography can be used to fabricate complex ceramic parts layer by layer through the photopolymerisation of ceramic suspensions. The broadening or lateral overcure of the curing shape occurs because of light scattering effects. Achieving a better dimension and strength quality by adjusting light energy delivery in the boundary mask area has been insufficiently investigated thus far. In this study, the conventional mask was segmented into boundary and interior masks. The exposure time and power of the boundary mask (two pixels wide) were varied to investigate the effects of segmented exposure. The segmented exposure constrained the dimension errors to a width of within two pixels for a feature dimension of less than 1200 µm. It further smoothed the lateral surface of the green part to achieve Ra values of below 6 µm. Moreover, enhancing the boundary mask increased the flexural strength and Weibull modulus to 248 MPa and 11.1, respectively. The results indicate that segmented exposure can potentially be used in complex lattice ceramic structures.

Indium thin oxide (ITO)-free planar perovskite solar cells (PSCs) were fabricated at a low temperature (150 &deg, C) in this work based on the transparent electrode of photolithography processed nickel/gold (Ni/Au) mesh and the high conductivity polymer, PH1000. Ultrathin Au was introduced to increase the conductivity of metal mesh, and the optimal hexagonal Ni (30 nm)/Au (10 nm) mesh (line width of 5 &mu, m) shows a transmittance close to 80% in the visible light region and a sheet resistance lower than 16.9 &Omega, /sq. The conductive polymer PH1000 not only smooths the raised surface of the metal mesh but also enhances the charge collection ability of metal mesh. The fabricated PSCs have the typical planar structure (glass/Ni-Au mesh/PH1000/PEDOT:PSS/MAyFA1&minus, yPbIxCl3&minus, x/PCBM/BCP/Ag) and the champion PSC (0.09 cm2) obtains a power conversion efficiency (PCE) of 13.88%, negligible current hysteresis, steady current density and PCE outputs, and good process repeatability. Its photovoltaic performance and stability are comparable to the reference PSC based on the ITO electrodes (PCE = 15.70%), which demonstrates that the Ni/Au mesh transparent electrodes are a promising ITO alternative to fabricate efficient PSCs. The relatively lower performance of Ni/Au based PSC results from the relatively slower charge extraction and stronger charge recombination than the ITO based PSC. Further, we tried to fabricate the large area (1 cm2) device and achieve a PCE over 6% with negligible hysteresis and steady current density and PCE outputs. The improvements of perovskite film quality and interface modification should be an effective approach to further enhance the device performance of Ni/Au based PSCs, and the Ni/Au mesh electrode may find wider applications in PSCs and flexible devices.

In this letter, planar floating limiting rings (FLRs) and trench FLRs with different trench depths for the 4H-SiC junction barrier Schottky (JBS) rectifiers are analyzed and compared with simulations and experiments. Compared with the planar FLRs, the experimental results present that the first ring spacing window that termination efficiency exceeds 80% of the parallel plane breakdown voltage (BV) can be widened and termination area can be reduced at the same BV by adopting the trench FLRs. The simulations also indicate that there is an optimal trench depth for the trench FLRs and a smaller sidewall angle can achieve better device performance. Additionally, the repetitive avalanche current stress measurements imply that the trench FLRs has better robustness regarding the BV shift, achieving better device reliability.

Hysteresis current–voltage (I–V) characteristics are often observed in a highly non-ideal (n > 2) as-deposited nickel (Ni)/4H-SiC Schottky contact. However, we find that this kind of hysteresis effect also exists in an as-deposited Ni/n-type 4H-SiC Schottky structure even if the ideality factor (n) is less than 1.2. The hysteresis I–V characteristics is studied in detail in this paper by using the various measurements including the hysteresis I–V, sequential I–V sweeping, cycle I–V, constant reverse voltage stress (CRVS). The results show that the hysteresis I–V characteristics are strongly dependent on the sweeping voltage and post-deposition annealing (PDA). The high temperature PDA (800 °C) can completely eliminate this hysteresis. Meanwhile, the magnitude of the hysteresis effect is shown to decrease in the sequential I–V sweeping measurement, which is attributed to the fact that the electrons tunnel from the 4H-SiC to the localized states at the Ni/n-type 4H-SiC interface. It is found that the application of the reverse bias stress has little effect on the emission of those trapped electrons. And a fraction of the trapped electrons will be gradually released with the time under the condition of air and with no bias. The possible physical charging mechanism of the interface traps is discussed on the basis of the experimental findings.

In this paper, a comparison of different floating junction structure underneath the termination region FJt for 4H-SiC FJ_JBS is performed by simulations and experiments. The simulated results indicate that the optimized dose of FJt is different when the different FJt structures are chosen, which is resulting from different work mechanism. The experimental results show that the breakdown voltage of FJ_JBS with discontinuous floating junction structure underneath the termination region is 2.9 kV. For comparison, the FJ_JBS with continuous floating junction structure without fixed outer boundary underneath the termination only achieves a breakdown voltage of 2.05 kV, which validates the simulation results.