Papers by Keyword: PN Diode

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Authors: N.I. Kuznetsov, D. Bauman, A. Gavrilin, Liliana Kassamakova, Roumen Kakanakov, G. Sarov, T. Cholakova, Konstantinos Zekentes, Ventzislav I. Dimitrov
Authors: Geun Ho Song, Hyoung Wook Kim, Wook Bahng, Sang Cheol Kim, Nam Kyun Kim
Authors: Michael Treu, Roland Rupp, Chee Siew Tai, Peter Blaschitz, Jochen Hilsenbeck, Helmut Brunner, Dethard Peters, Rudolf Elpelt, T. Reimann
Abstract: Today silicon carbide (SiC) Schottky diodes are mainly used in the power factor control (PFC) unit of high end switched mode power supplies, due to their outstanding switching performance compared to Si pn diodes. In the case of the PFC it is required that the diodes are capable of handling surge currents up to several times the current of normal operation. The paper shows the surge current capability of a merged pn Schottky diode where the p-areas are optimized as efficient emitters. During normal operation the diode is behaving like a normal Schottky diode whereas during surge current condition the diode is behaving like a pn diode. For a sine half wave of 10 ms we achieved a non repetitive peak forward current capability of about 3700 A/cm2 which is about ten times rated current (for comparison: destructive current density of a standard Schottky diode ~ 1650 A/cm²). Additionally the device shows a stable avalanche and is able to withstand a single shot avalanche of 9.5 3s and 12.5 mJ.
Authors: Yoshitaka Sugawara
Abstract: To achieve large current capability in spite of present small SiC devices that are limited by various crystal defects, focus was placed on SiC GTO thyristor and SICGT have been developed as an advanced SiC GTO. SICGTs with current capability of 1.6-100 A and blocking voltage of 3-12.7 kV and a 3 phase PWM SICGT inverter with output power of 35 kVA have been successfully developed. Furthermore, application of the SiC inverter aimed to a load leveling system was demonstrated.
Authors: Syunsuke Izumi, Isaho Kamata, Takeshi Tawara, Hiroyuki Fujisawa, Hidekazu Tsuchida
Authors: Satoshi Torimi, Norihito Yabuki, Takuya Sakaguchi, Masato Shinohara, Yoji Teramoto, Satoru Nogami, Makoto Kitabatake, Junji Senzaki
Abstract: We investigate electrical characteristics of the pn-diode fabricated using the epitaxial films on the surface damage-free 4H-SiC (0001) Si-face 4° off-cut wafers prepared by the completely thermal-chemical etching process; Si-vapor etching (Si-VE) technology. The forward and reverse current-voltage (I-V) characteristics of pn-diodes correlated to the epitaxial defects are discussed. The device at the defect-free area includes 11 % failed diodes on the chemo-mechanical polishing (CMP) wafer while 0 % on the Si-VE wafer. The latent scratches and mechanical damages, which increase the forward and reverse leakage current of the pn-diodes, are completely removed by the Si-VE. The Si-VE exposes the carbon inclusions in the wafer to form the small bump which ends up with the larger bump defect on the epitaxial surface. These bumps cause leak current of the forward characteristics while all of the reverse characteristics are normal. The epitaxial film on the Si-VE surface has less density of the basal plane dislocations (BPDs) than the conventional CMP. It is hard to recognize the safe device on the CMP wafer without additional reliability test. The Si-VE wafer shows the apparent breakdown voltage fail on every small-number diode including BPDs under the simple test. It is considered that the Si-VE is possible to reduce ambiguity of the device characteristics under the relationship with the defects in comparison with the CMP.
Authors: Takeshi Ohshima, Takahiro Satoh, Masakazu Oikawa, Shinobu Onoda, Toshio Hirao, Hisayoshi Itoh
Abstract: The charge generated in 6H-SiC n+p diodes by oxygen (O) ion irradiation at energies between 6 and 15 MeV was evaluated using the Transient Ion Beam Induced Current (TIBIC). The signal peak of the transient current increases, and the fall-time decreases with increasing applied reverse bias. The value of collected charge increases with increasing applied reverse bias, and the saturation of the collected charge was observed in high reverse bias regions (e.g. above 70 V in the case of 12MeV O-irradiation). The charge generated in the deeper region than the depletion layer is collected due to the "funneling effect". Almost all charge generated in n+p SiC diodes by O-irradiation between 6 and 15 MeV is collected when the length of the depletion layer becomes longer than the projection range of ions.
Authors: M.V.S. Chandrashekhar, Christopher I. Thomas, Hui Li, Michael G. Spencer, Amit Lal
Abstract: A betavoltaic cell in 4H SiC is demonstrated. An abrupt p-n diode structure was used to collect the charge from a 1mCi Ni-63 source. An open circuit voltage of 0.95V and a short circuit current density of 8.8 nA/cm2 were measured in a single p-n junction. An efficiency of 3.7% was obtained. A simple photovoltaic type model was used to explain the results. Good correspondence with the model was obtained. Fill factor and backscattering effects were included. Efficiency was limited by edge recombination and poor fill factor.
Authors: Yasunori Tanaka, Kazutoshi Kojima, Takaya Suzuki, T. Hayashi, Kenji Fukuda, Tsutomu Yatsuo, Kazuo Arai
Authors: Yohei Iwahashi, Masaki Miyazato, Masaaki Miyajima, Yoshiyuki Yonezawa, Tomohisa Kato, Hirokazu Fujiwara, Kimimori Hamada, Akihiro Otsuki, Hajime Okumura
Abstract: We investigated the expansion of stacking faults (SFs) under a high current pulse stress in detail. In situ observations showed bar-shaped SFs and two types of triangle SFs with different nucleation sites. The calculated partial dislocation velocity of the bar-shaped SFs was four times faster than that of the triangle SFs. The temperature dependence of the partial dislocation velocity was used to estimate activation energies of 0.23±0.02 eV for bar-shaped SFs and 0.27±0.05 eV for triangle SFs. We also compared the electrical characteristics before and after the stress. The forward voltage drop slightly increased by 0.05 V, and the leakage current did not increase.
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