Yoshiyuki Yonezawa

Learn More
Ultrahigh-voltage silicon carbide (SiC) devices [p-i-n diodes and insulated-gate bipolar transistors (IGBTs)] and switching test have been investigated. As a result, we have succeeded in developing a 13-kV p-i-n diode, 15-kV p-channel IGBT, and 16-kV flip-type n-channel implantation and epitaxial IGBT with a low differential specific on-resistance(More)
We propose another process for fabricating 4H-SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) with high channel mobility. The B atoms were introduced into a SiO<sub>2</sub>/4H-SiC interface by thermal annealing with a BN planar diffusion source. The interface state density near the conduction band edge of 4H-SiC was effectively reduced by(More)
4H-SiC carbon face flip-type n-channel implantation and epitaxial (IE)-IGBT with an epitaxial p<sup>++</sup> substrate was developed and its switching test was carried out. We were able to achieve an ultrahigh blocking voltage greater than 16 kV, extremely low V<sub>on</sub> (6.35 V at 20 A), and good temperature stability. The switching operation was(More)
Flip-type n-channel implantation and epitaxial (IE)-IGBT on 4H-SiC carbon face with an epitaxial p<sup>++</sup> collector layer was investigated. In this study, we employed the IEMOSFET as a MOSFET structure with original wet gate oxidation method, to realize high channel mobility. We were able to achieve an ultrahigh blocking voltage of more than 16 kV,(More)
Ultrahigh voltage SiC bipolar devices more than 13 kV were developed, and their package technology was investigated. As a result, we have succeeded in creating a 13kV level PiN diode without forward voltage degradation by using 4&#x00B0; off substrates and a 15kV p-channel IGBT with a low differential specific on-resistance (R<sub>diff,on</sub>) at high(More)
Ultrahigh voltage SiC devices and their package technology were investigated. As a result, we have succeeded in creating a 13kV level PiN diode without forward voltage degradation by using 4&#x00B0; off substrates and a 15kV level p-channel IGBT and 16kV level n-channel IGBT with a low differential specific on-resistance (R<sub>diff,on</sub>). Moreover, the(More)
Trench-filling epitaxial growth of 4H-SiC was analyzed based on a simulation model for continuous fluid approximation (as opposed to molecular beam approximation) including the Gibbs-Thomson effect. With the use of the radii of curvature at the top and bottom of the trenches, the proposed model well reproduced the measured dependence of the growth rate on(More)
Application of highly N-doped buffer layers or a (N&#x002B;B)-doped buffer layer to PiN diodes to suppress the expansion of Shockley stacking faults (SSFs) from the epilayer/substrate interface was studied. These buffer layers showed very short minority carrier lifetimes of 30&#x2013;200 ns at 250&#x00B0;C. The PiN diodes were fabricated with buffer layers(More)
Impacts of extended defects on performance and reliability of SiC power devices are reviewed. Threading dislocations in the state-of-the-art SiC wafers do not work as the major leakage paths and macroscopic defects generated during epitaxial process are more harmful. A basal plane dislocation is a killing defect in SiC bipolar devices because a(More)
To examine the effect of the device structure on the on-state voltage (V<sub>on</sub>), several types of ultrahigh-voltage 4H-SiC p-channel insulated-gate bipolar transistors (IGBTs) were fabricated. A p-channel IGBT with a retrograde charge storage layer (CSL) and an additional JFET ion implantation region exhibited the lowest V<sub>on</sub> at 200(More)