Papers by Author: Heinz Mitlehner

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Authors: Julietta Weiße, Martin Hauck, Tomasz Sledziewski, Mattias Tschiesche, Michael Krieger, Anton J. Bauer, Heinz Mitlehner, Lothar Frey, Tobias Erlbacher
Abstract: In this work, we analyze compensating defects which are formed after implantation of aluminum (Al) into n-type 4H-SiC epitaxial layers and subsequent thermal annealing. These defects reduce the expected free charge carrier density by 84% for a low doped layer with [Al]impl ≈ 9ž·1016 cm-3 and by 27 % for a high doped layer with [Al]impl ≈ 2·ž1019 cm-3. Furthermore, an electrical activation ratio of implanted aluminum ions of 100 % is calculated. The ionization energy of implanted aluminum as measured by Hall effect and admittance spectroscopy ranges from 101 meV to 305 meV depending on the doping concentration.
Authors: Peter Friedrichs, Heinz Mitlehner, Reinhold Schörner, Karl Otto Dohnke, Rudolf Elpelt, Dietrich Stephani
Authors: Heinz Mitlehner, Peter Friedrichs, Rudolf Elpelt, Karl Otto Dohnke, Reinhold Schörner, Dietrich Stephani
Authors: Wolfgang Bartsch, Heinz Mitlehner, S. Gediga
Abstract: In this contribution we summarize measurements on bipolar high voltage SiC-diodes which were fabricated on 4H-SiC wafers preferentially cut 4° off the [0001] basal plane, whereas the p-emitter thickness was varied in predetermined ratios to the n-base thickness. The switching behaviour of optimized 6.5 kV-Diodes at a current level of 25 A is shown at DC link voltages up to 4 kV and at a junction temperature of 125°C. Experimental results are discussed in terms of snappiness.
Authors: Volker Haeublein, Gerhard Temmel, Heinz Mitlehner, Gudrun Rattmann, Christian Strenger, Andreas Hürner, Anton J. Bauer, Heiner Ryssel, Lothar Frey
Abstract: N-LDMOS and n-LIGBT structures were manufactured with the same dimensions on a 4H-SiC wafer in order to allow for a direct comparison. The comparison of the devices includes output and transfer characteristics, blocking characteristics, and temperature behavior.
Authors: Andreas Hürner, Heinz Mitlehner, Tobias Erlbacher, Anton J. Bauer, Lothar Frey
Abstract: In this study, the potential of forward conduction loss reduction of Bipolar-Injection Field-Effect-Transistors (SiC-p-BIFET) with an intended blocking voltage of 10kV by adjusting the doping concentration in the channel-region is analyzed. For the optimization of the SiC-p-BIFET, numerical simulations were carried out. Regarding a desired turn-off voltage of approximately 25V, the optimum doping concentration in the channel-region was found to be 1.4x1017cm-3. Based on these results, SiC-p-BIFETs were fabricated and electrically characterized in the temperature range from 25°C up to 175°C. In this study, the differential on-resistance was found to be 110mΩcm2 for a temperature of 25°C and 55mΩcm2 for a temperature of 175°C. In comparison to our former results, a reduction of the differential on-resistance of about 310mΩcm2 at room temperature is demonstrated.
Authors: Peter Friedrichs, Heinz Mitlehner, Reinhold Schörner, Karl Otto Dohnke, Dietrich Stephani
Authors: Peter Friedrichs, Heinz Mitlehner, Reinhold Schörner, Rainer Kaltschmidt, Karl Otto Dohnke, Dietrich Stephani
Authors: Peter Friedrichs, Rudolf Elpelt, Reinhold Schörner, Heinz Mitlehner, Dietrich Stephani
Authors: Andreas Hürner, Luigi di Benedetto, Tobias Erlbacher, Heinz Mitlehner, Anton J. Bauer, Lothar Frey
Abstract: In this study, a new robust double-ring junction-termination-extension (DR-JTE) for high-voltage pn-diodes is presented and analyzed using numerical simulations. As figured out, the DR-JTE reduces the electrical field at both, the edge of the single-JTE region and the MESA-transition, respectively. Thereby, due to the reduction of the electrical field, the maximum breakdown voltage is increased to 91.5% of the theoretical, parallel-plane breakdown voltage of 6.5kVand the maximum acceptable deviation of the optimum implantations dose is twice than that of the single-JTE structure. Furthermore, due to the internal ring, the MESA-transition is shielded from the electrical field and therefore the breakdown voltage is much less affected by the angle of the MESA.
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