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323 results on '"Grossner, Ulrike"'

101. Sensitivity of Dit Extraction at the SiO2/SiC Interface Using Quasi-Static Capacitance-Voltage Measurements

Author

Belanche, Manuel, Kumar, Piyush, Woerle, Judith, Stark, Roger, and Grossner, Ulrike

Abstract

In this work, we compare different quasi-static capacitance-voltage measurement systems by analyzing 4H-SiC n-type MOS capacitors and studying the influence of systematic errors when extracting the interface trap density (Dit). We show that the extracted Dit strongly depends on the calculation of the surface potential due to variations of the integration constant. In addition, the ramp-rate during the quasi-static measurement is identified as a sensitive measurement parameter whose noise level is amplified in the Dit extraction.

Published
2022
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102. Depth-Resolved Study of the SiO2- SiC Interface Using Low-Energy Muon Spin Rotation Spectroscopy

Author

Kumar, Piyush, Martins, Maria Inês Mendes, Bathen, Marianne Etzelmüller, Woerle, Judith, Prokscha, Thomas, and Grossner, Ulrike

Abstract

In this work, the interface between 4H-SiC and thermally grown SiO2 is studied using low energy muon spin rotation (LE-μSR) spectroscopy. Samples oxidized at 1300 °C were annealed in NO or Ar ambience and the effect of the ambience and the annealing temperature on the near interface region is studied in a depth resolved manner. NO-annealing is expected to passivate the defects, resulting in reduction of interface traps, which is confirmed by electrical characterization. Introduction of N during annealing, to the SiC matrix, results in a thin, carrier rich region close to the interface leading to an increase in the diamagnetic asymmetry. Annealing in an inert environment (Ar) seems to have much lesser impact on the electrical signal, however the μSR shows a reduced paramagnetic asymmetry, indicating a narrow region of low mobility at the interface.

Published
2022
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103. Temperature Dependence of On-State Inter-Terminal Capacitances (Cgd and Cgs) of SiC MOSFETs and Frequency Limitations of their Measurements

Author

Tsibizov, Alexander, Stark, Roger, and Grossner, Ulrike

Abstract

Inter-terminal capacitances (ITCs) have major influence on the dynamic performance of power SiC MOSFETs. Knowledge of the exact values for the ITCs is required in order to perform accurate and predictive compact model simulations of their dynamic performance. Since commercial SiC MOSFETs are capable of operating in a wide range of temperatures, it is important to know the values of ITCs in the whole temperature range of operation. Direct measurements of the ITCs with standard equipment is possible only at low current levels (i.e. in the off-state (Vgs < Vth) for Vds > 0 V), however their values in the on-state (Vgs>Vth) also influence the MOSFETs switching performance. In this work, ITCs of a planar SiC MOSFET in the on-state are studied by the means of a calibrated TCAD model, revealing substantial temperature dependence in the range of 300-450 K. In the first approximation, this temperature dependence of the ITCs can be explained by a weaker temperature dependence of the MOSFET channel resistance in comparison to its JFET and epitaxial layer resistances. In addition, it is shown that at high frequencies stray inductances of the TO-247-3 package result in a change of the extracted values of the on-state ITCs. This effect is already notable at 1 MHz.

Published
2022
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107. Towards Full Silicon 4H-SiC Based X-Ray Beam Monitoring

Author

Camarda, Massimo, Birri, Mario, Carulla, Maria, Grolimund, Daniel, Grossner, Ulrike, Meyer, Beat, Nida, Selamnesh, Pradervand, Claude, Tsibizov, Alexander, and Ziemann, Thomas

Subjects
Beam position monitors, Accelerator Physics
Abstract

In this work, we present extensive theoretical and experimental results of novel Silicon Carbide x-ray sensors for beam position monitoring (XBPM). Until recently, diamond, was considered the material-of-choice for continuous monitoring of hard (>6keV) x-ray beams at synchrotron light sources. Diamond XBPM are now commercially available as single crystal* and polycrystalline** sensors. However, in a recently published paper***, we have shown that Silicon Carbide is superior to both diamond crystal types in several critical aspects. Specifically, we found superior electrical characteristics (sensor dynamics, signal uniformity, signal strength) and superior optical properties (full device transparency, device active area, signal strength) when compared to commercial polycrystalline and single crystal diamond, respectively. We also succeeded in the ¿industrialization¿ of the SiC fabrication process, allowing for the simultaneous realization of several (>40) sensors in up to 4¿ SiC wafers, with high yields. More recently we have also analyzed the fluorescence of SiC sensors as compared to YAG ones, finding that SiC can also be used for hybrid position/shape monitoring schema., Proceedings of the 8th International Beam Instrumentation Conference, IBIC2019, Malmö, Sweden

Published
2019
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108. Cartographie bidimensionnelle des défauts à l'interface SiO2 / 4H-SiC

Author

Woerle, Judith, Johnson, Brett, Bongiorno, Corrado, Yamasue, Kohei, Ferro, Gabriel, Dutta, Dipanwita, Jung, Thomas, Sigg, Hans, Cho, Yasuo, Grossner, Ulrike, Camarda, Massimo, Paul Scherrer Institute (PSI), School of Physics [Melbourne], Faculty of Science [Melbourne], University of Melbourne-University of Melbourne, Istituto per la Microelettronica e Microsistemi [Catania] (IMM), Consiglio Nazionale delle Ricerche (CNR), Research Institute of Electrical Communication [Sendai] (RIEC), Tohoku University [Sendai], Laboratoire des Multimatériaux et Interfaces (LMI), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Physics Department (ETHZ), and Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)

Subjects
[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]
Abstract

International audience; Current generations of 4H-SiC metal-oxide-semiconductor field-effect transistors are still challenged by the high number of defects at the SiO 2 /SiC interface that limit both the performance and gate reliability of these devices. One potential source of the high density of interface defect states (D it) is the stepped morphology on commonly used off-axially grown epitaxial surfaces, favoring incomplete oxidation and the formation of defective transition layers. Here we report measurements on intentionally modified 4H-SiC surfaces exhibiting both atomically flat and stepped regions where the generation of interface defects can be directly linked to differences in surface roughness. By combining spatially resolving structural, chemical, optical, and electrical analysis techniques, a strong increase of D it for stepped surfaces was revealed while regions with an atomically flat SiC surface exhibited close-to-ideal interface properties.

Published
2019

110. Parasitic Extraction Procedures for SiC Power Modules

Author

Kovacevic-Badstuebner, Ivana, Stark, Roger, Guacci, Mattia, Kolar, Johann W., Grossner, Ulrike, and Energietechnische Gesellschaft im VDE (ETG)

Abstract

10th International Conference on Integrated Power Electronics Systems, Proceedings March, 20 – 22, 2018, Stuttgart/Germany, ISBN:978-3-8007-4540-1

Published
2018
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113. Two-dimensional defect mapping of the SiO2/4H−SiC interface

Author

Woerle, Judith, primary, Johnson, Brett C., additional, Bongiorno, Corrado, additional, Yamasue, Kohei, additional, Ferro, Gabriel, additional, Dutta, Dipanwita, additional, Jung, Thomas A., additional, Sigg, Hans, additional, Cho, Yasuo, additional, Grossner, Ulrike, additional, and Camarda, Massimo, additional

Published
2019
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115. Surface Morphology of 4H-SiC after Thermal Oxidation

Author

Woerle, Judith, primary, Šimonka, Vito, additional, Müller, Elisabeth, additional, Hössinger, Andreas, additional, Sigg, Hans, additional, Selberherr, Siegfried, additional, Weinbub, Josef, additional, Camarda, Massimo, additional, and Grossner, Ulrike, additional

Published
2019
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120. Silicon carbide X-ray beam position monitors for synchrotron applications

Author

Nida, Selamnesh, primary, Tsibizov, Alexander, additional, Ziemann, Thomas, additional, Woerle, Judith, additional, Moesch, Andy, additional, Schulze-Briese, Clemens, additional, Pradervand, Claude, additional, Tudisco, Salvatore, additional, Sigg, Hans, additional, Bunk, Oliver, additional, Grossner, Ulrike, additional, and Camarda, Massimo, additional

Published
2019
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131. Electrical properties of Al2O3/4H-SiC structures grown by atomic layer chemical vapor deposition.

Author

Avice, Marc, Grossner, Ulrike, Pintilie, Ioana, Svensson, Bengt G., Servidori, Marco, Nipoti, Roberta, Nilsen, Ola, and Fjellvåg, Helmer

Subjects
*ALUMINUM oxide, *CHEMICAL vapor deposition, *CAPACITORS, *CONDUCTION bands, *DIELECTRIC relaxation, *OXIDATION, *METAL oxide semiconductors
Abstract

Al2O3 films have been deposited on n-type and p-type 4H-SiC by atomic layer chemical vapor deposition using trimethylaluminum as a precursor for aluminum and both H2O and O3 as an oxidant. After oxide deposition, annealing at different temperatures (800, 900, 1000 °C) in argon atmosphere for different durations (1, 2, 3 h) was performed. Bulk and interface properties of the oxide films were studied by capacitance-voltage, current-voltage, deep level transient spectroscopy, and thermally dielectric relaxation current (TDRC) measurements. The results reveal a decreasing flatband voltage with increasing annealing time, suggesting decrease of oxide charges and deep interface traps. After 3 h annealing at 1000 °C of the n-type samples, the flatband voltage is reduced to 6 V compared to a value in excess of 40 V for as-deposited samples. The TDRC measurements on annealed Al2O3/SiC (n-type) capacitors showed substantially different spectra relative to conventional SiO2/4H-SiC control samples; in the former ones no signal was recorded at temperatures less than 100 K, demonstrating a low density of shallow electron traps below the conduction band edge of 4H-SiC and hence a prospect of obtaining a high electron channel mobility in 4H-SiC metal-oxide-semiconductor field-effect devices with Al2O3 as gate dielectric. [ABSTRACT FROM AUTHOR]

Published
2007
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132. 1950°C annealing of Al+ implanted 4H-SiC: Sheet resistance dependence on the annealing time

Author

Nipoti, Roberta, Parisini, Antonella, Vantaggio, Salvatore, Alfieri, Giovanni, Carnera, Alberto, Centurioni, Emanuele, Elmi, Ivan, and Grossner, Ulrike

Subjects
4H-SiC, Post implantation annealing time, Al doping by ion implantation
Abstract

This study shows that, after annealing at 1950°C, a 1×1020 cm Al implanted 4H-SiC material shows a decreasing resistivity with increasing annealing time in the range 5-25 min. After this, the resistivity remains constant up to an annealing time of 40 min. The estimated minimum time to gain the thermal equilibrium in this implanted material at 1950°C is 12 min. Electrical characterization has been performed in the 20-680 K temperature range.

Published
2016
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133. Electrical properties of [Al.sub.2][O.sub.3]/4H-SiC structures grown by atomic layer chemical vapor deposition

Author

Avice, Marc, Grossner, Ulrike, Pintilie, Ioana, Svensson, Bengt G., Servidori, Marco, Nipoti, Roberta, Nilsen, Ola, and Fjellvag, Helmer

Subjects
Aluminum compounds -- Structure, Aluminum compounds -- Chemical properties, Aluminum compounds -- Thermal properties, Chemical vapor deposition -- Analysis, Voltage -- Measurement, Physics
Abstract

The electrical characteristics and thermal stability of [Al.sub.2][O.sub.3] gate oxide layers deposited by atomic layer chemical vapor deposition (ALCVD) on 4H-SiC are described. The results have shown a decreasing flatband voltage with increasing annealing time, which has indicated decrease of oxide charges and deep interface traps.

Published
2007

140. Ni-Al-Ti Ohmic Contacts on Al Implanted 4H-SiC

Author

Fedeli, P., primary, Puzzanghera, Maurizio, additional, Moscatelli, Francesco, additional, Minamisawa, Renato Amaral, additional, Alfieri, Giovanni, additional, Grossner, Ulrike, additional, and Nipoti, Roberta, additional

Published
2017
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142. Al+ ion implanted on-axis <0001>semi-insulating 4H-SiC

Author

Nipoti, Roberta, Parisini, Antonella, Carnera, Alberto, Albonetti, Cristiano, Vantaggio, Salvatore, and Grossner, Ulrike

Subjects
Ion implantation, On-axis 4H-SiC, P-type doping
Abstract

P-type 4H-SiC layers have been obtained by different 400°C Al ion implantation processes of semi insulating 4H-SiC wafers and identical 1950°C/5 min post implantation annealing. Implanted Al concentration have been 4.7×10, 9.3×10, and 4.7×10 cm, thickness of the implanted layer about 630 nm. Electrical characterizations have been performed in the temperature range 100 - 580 K. With decreasing temperature, the onset of a hole conduction through an impurity band has been seen for all the specimens.

Published
2015
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