| 1. |
- Eless, V., et al.
(författare)
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Controlling the carrier concentration of epitaxial graphene by ultraviolet illumination
- 2014
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Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2. - Switzerland : Trans Tech Publications. - 9783038350101 ; , s. 1137-1141
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Konferensbidrag (refereegranskat)abstract
- Silicon carbide (SiC) is a well-known material for UV detection however the effect of UV illumination on the electron donation between the substrate, interfacial (or buffer layer) and graphene is not well understood. The effect of ultraviolet (UV) illumination on the carrier concentration of an epitaxial graphene hall bar device is investigated by scanning Kelvin probe microscopy (SKPM) and transport measurements in ambient and vacuum conditions. Modulation of the carrier concentration is demonstrated and shown to be due to both substrate and environmental effects.
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| 2. |
- Florentin, M., et al.
(författare)
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Rapid thermal oxidation of Si-Face N and P-type on-axis 4H-SiC
- 2014
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Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2. - : Trans Tech Publications. - 9783038350101 ; , s. 591-594
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Konferensbidrag (refereegranskat)abstract
- This paper deals with the comparison of several MOS structures with different rapid thermal oxidation processes (RTO) carried out on Off and On-axis SiC material. A first set contains MOS capacitance structures on n-epitaxial layers, while a second set of MOS capacitance are built on p-implanted layers. Both sets include On and Off-Axis angle cuts. Furthermore, n-MOSFETs have been fabricated on On-axis p-type Al-implanted layers with the best oxidation process selected from the MOS capacitance study. The final objective is to show the performances of these On-axis p-implanted n-MOSFETs and to evidence the associated lower surface roughness at the SiO2/SiC interface.
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| 3. |
- Issa, F., et al.
(författare)
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Nuclear radiation detectors based on 4H-SiC p+-n junction
- 2014
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Ingår i: 15th International Conference on Silicon Carbide and Related Materials, ICSCRM 2013. - 9783038350101 ; , s. 1046-1049
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Konferensbidrag (refereegranskat)abstract
- Silicon carbide (SiC) radiation detectors were realized by 10B implantation into the metal contact in order to avoid implantation-related defects within the sensitive area of the 4H-SiC pn junction. No post implantation annealing was performed. Such detectors respond to thermal neutrons showing consistent counting rates as function of external reverse bias voltages and radiation intensity.
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| 4. |
- Kallinger, B., et al.
(författare)
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Comparison of carrier lifetime measurements and mapping in 4H SIC using time resolved photoluminescence and μ-PCD
- 2014
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Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2. - Stafa-Zurich, Switzerland : Trans Tech Publications. - 9783038350101 ; , s. 301-304
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Konferensbidrag (refereegranskat)abstract
- Carrier lifetime measurements and wafer mappings have been done on several different 4H SiC epiwafers to compare two different measurement techniques, time-resolved photoluminescence and microwave induced photoconductivity decay. The absolute values of the decay time differ by a factor of two, as expected from recombination and measurement theory. Variations within each wafer are comparable with the two techniques. Both techniques are shown to be sensitive to substrate quality and distribution of extended defects.
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| 5. |
- Lanni, Luigia, et al.
(författare)
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SiC Etching and Sacrificial Oxidation Effects on the Performance of 4H-SiC BJTs
- 2014
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Ingår i: Materials Science Forum. - : Trans Tech Publications Inc.. - 0255-5476 .- 1662-9752. - 9783038350101 ; 778-780, s. 1005-1008
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Tidskriftsartikel (refereegranskat)abstract
- Performance of 4H-SiC BJTs fabricated on a single 100mm wafer with different SiC etching and sacrificial oxidation procedures is compared in terms of peak current gain in relation to base intrinsic sheet resistance. The best performance was achieved when device mesas were defined by inductively coupled plasma etching and a dry sacrificial oxide was grown at 1100 °C.
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| 6. |
- Lim, Jang-Kwon, et al.
(författare)
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Evaluation of buried grid JBS diodes
- 2014
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Ingår i: 15th International Conference on Silicon Carbide and Related Materials, ICSCRM 2013. - : Trans Tech Publications Inc.. - 9783038350101 ; , s. 804-807
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Konferensbidrag (refereegranskat)abstract
- The 4H-SiC Schottky barrier diodes for high temperature operation over 200 °C have been developed using buried grids formed by implantation. Compared to a conventional JBS-type SBD with surface grid (SG), JBS-type SBD with buried grid (BG) has significantly reduced leakage current at reverse bias due to a better field shielding of the Schottky contact. By introducing the BG technology, the 1.7 kV diodes with an anode area 0.0024 cm2 (1 A) and 0.024 cm2 (10 A) were successfully fabricated, encapsulated in TO220 packages, and electrically evaluated. Two types of buried grid arrangement with different grid spacing dimensions were investigated. The measured IV characteristics were compared with simulation. The best fit was obtained with an active area of approximately 60% and 70% of the anode area in large and small devices, respectively. The measured values of the device capacitances were 1000 pF in large devices and 100 pF in small devices at zero bias. The capacitance values are proportional to the device area. The recovery behavior of big devices was measured in a double pulse tester and simulated. The recovery charge, Qc, was 18 nC and 24 nC in simulation and measurement, respectively. The fabricated BG JBS-type SBDs have a smaller maximum reverse recovery current compared to the commercial devices. No influence of the different grid spacing on the recovery charge was observed.
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| 7. |
- Nee, Hans-Peter, 1963-, et al.
(författare)
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High-Efficiency Power Conversion Using Silicon Carbide Power Electronics
- 2013
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Ingår i: Proc. of International Conference on silicon carbide and related materials (ICSCRM) 2013, Miyazaki, Japan, Sept. 29–Oct. 4, 2013. - : Trans Tech Publications Inc.. - 9783038350101 ; 778-780
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Konferensbidrag (refereegranskat)abstract
- The message of this paper is that the silicon carbide power transistors of today are good enough to design converters with efficiencies and switching speeds beyond comparison with corresponding technology in silicon. This is the time to act. Only in the highest power range the devices are missing. Another important step towards high powers is to find new solutions for multi-chip circuit designs that are adapted to the high possible switching speeds of unipolar silicon carbide power transistors.
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| 8. |
- Roensch, Sebastian, et al.
(författare)
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Drain-current deep level transient spectroscopy investigation on epitaxial graphene/6H-SiC field effect transistors
- 2014
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Ingår i: Mater. Sci. Forum. - 9783038350101 ; , s. 436-439
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Konferensbidrag (refereegranskat)abstract
- The electrically active deep levels in a graphene/silicon carbide field effect transistor (FET) were investigated by drain-current deep level transient spectroscopy (ID-DLTS). An evaluation procedure for ID-DLTS is developed in order to obtain the activation energy, the capture cross section and the trap concentration. We observed three defect centers corresponding to the intrinsic defects E1/E2, Ei and Z1/Z2 in n-type 6H-SiC. The determined parameters have been verified by conventional capacitance DLTS.
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| 9. |
- Salemi, Arash, et al.
(författare)
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Fabrication and Design of 10 kV PiN Diodes Using On-axis 4H-SiC
- 2014
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Ingår i: Materials Science Forum. - : Trans Tech Publications. - 0255-5476 .- 1662-9752. - 9783038350101 ; 778-780, s. 836-840
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Tidskriftsartikel (refereegranskat)abstract
- 10 kV PiN diodes using on-axis 4H-SiC were designed, fabricated, and measured. A lifetime enhancement procedure was done by carbon implantation followed by high temperature annealing to increase lifetime to above 2 mu s. The device simulation software Sentaurus TCAD has been used in order to optimize the diode. All fabricated diodes are fully functional and have a V-F of 3.3 V at 100 A/cm(2) at 25 degrees C, which was decreased to 3.0 V at 300 degrees C.
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| 10. |
- Sledziewski, Tomasz, et al.
(författare)
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Reduction of density of 4H-SiC/SiO2 interface traps by pre-oxidation phosphorus implantation
- 2014
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Ingår i: Materials Science Forum. - 9783038350101 ; , s. 575-578
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Konferensbidrag (refereegranskat)abstract
- The effect of phosphorus (P) on the electrical properties of the 4H-SiC/SiO2 interface was investigated. Phosphorus was introduced by surface-near ion implantation with varying ion energy and dose prior to thermal oxidation. Secondary ion mass spectrometry revealed that only part of the implanted P followed the oxidation front to the interface. A negative flatband shift due to residual P in the oxide was found from C-V measurements. Conductance method measurements revealed a significant reduction of density of interface traps Dit with energy EC-Eit > 0.3 V for P+-implanted samples with [P]interface = 1.5 · 1018 cm-3 in the SiC layer at the interface. .
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| 11. |
- Smedfors, Katarina, et al.
(författare)
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Characterization of Ohmic Ni/Ti/Al and Ni Contacts to 4H-SiC from-40 degrees C to 500 degrees C
- 2014
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Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. - 9783038350101 ; 778-780, s. 681-684
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Tidskriftsartikel (refereegranskat)abstract
- Extreme temperature measurements of Ni/Ti/Al contacts to p-type SiC (N-a = 1.10(18)cm(-3)), with a specific contact resistivity rho(c) = 6.75.10(-4) Omega cm(2) at 25 degrees C, showed a five time increase of the specific contact resistivity at -40 degrees C (rho(c) = 3.16.10(-3) Omega cm(2)), and a reduction by almost a factor 10 at 500 degrees C (rho(c) = 7.49.10(-5) Omega cm(2)). The same response of rho(c) to temperature was seen for contacts on lower doped epitaxial layer. Also N-type nickel contacts improved with higher operational temperature but with a considerably smaller variation over the same temperature interval. No degradation of the performance was seen to either the Ni/Ti/Al or the Ni contacts due to the high temperature measurements.
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| 12. |
- Sveinbjörnsson, Einar, et al.
(författare)
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Deep traps in 4H-SiC MOS capacitors investigated by deep level transient spectroscopy
- 2014
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Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2. - Stafa-Zurich. Switzerland : Trans Tech Publications. - 9783038350101 ; , s. 603-606
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Konferensbidrag (refereegranskat)abstract
- Using Deep Level Transient Spectroscopy (DLTS) on n-type MOS capacitors we find that thermal oxidation of 4H-SiC produces deep traps at or near the SiO2/SiC interface with two well defined DLTS peaks. The traps are located ~ 0.85 V and ~ 1.0 eV below the SiC conduction band edge and are present in wet and dry oxides as well as oxides produced by sodium enhanced oxidation and oxides grown in N2O. The deep traps are located at the SiO/SiC interface after oxidation at 1150C but do extend further into the SiC epilayer after oxidation at 1240C. We identify these traps as ON1 and ON2 which been observed in epitaxial layers after oxidation at very high temperatures (1200-1500C) [1].
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| 13. |
- Szasz, K., et al.
(författare)
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First principles investigation of divacancy in SiC polytypes for solid state qubit application
- 2014
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Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2. - Stafa-Zurich, Switzerland : Trans Tech Publications. - 9783038350101 ; , s. 499-502
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Konferensbidrag (refereegranskat)abstract
- We calculated the hyperfine structure and the zero-field splitting parameters of divacancies in 3C, 4H and 6H SiC in the ground state and in the excited state for 4H SiC within the framework of density functional theory. Besides that our calculations provide identification of the defect in different polytypes, we can find some carbon atoms next to the divacancy that of the spin polarizations are similar in the ground and excited states. This coherent nuclear spin polarization phenomenon can be the base to utilize 13C spins as quantum memory.
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| 14. |
- Thierry-Jebali, N., et al.
(författare)
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Applications of vapor-liquid-solid selective epitaxy of highly p-type doped 4H-SiC: PiN diodes with peripheral protection and improvement of specific contact resistance of ohmic contacts
- 2014
-
Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2. - : Trans Tech Publications. - 9783038350101 ; , s. 639-644
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Konferensbidrag (refereegranskat)abstract
- This work deals with two applications of the Selective Epitaxial Growth of highly p-type doped buried 4H-SiC in Vapor-Liquid-Solid configuration (SEG-VLS). The first application is the improvement of the Specific Contact Resistance (SCR) of contacts made on such p-type material. As a result of the extremely high doping level, SCR values as low as 1.3x10-6 Ω.cm2 have been demonstrated. Additionally, the high Al concentration of the SEG-VLS 4H-SiC material induces a lowering of the Al acceptor ionization energy down to 40 meV. The second application is the fabrication of PiN diodes with SEG-VLS emitter and guard-rings peripheral protection. Influence of some process parameters and crystal orientation on the forward and reverse characteristics of the PiN diodes is discussed. © (2014) Trans Tech Publications, Switzerland.
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| 15. |
- Toth-Pal, Zsolt, et al.
(författare)
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Pressure dependence of thermal contact resistance between copper heat sink and copper DBC surfaces in SiC power device packages
- 2014
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Ingår i: Silicon Carbide and Related Materials 2013. - : Trans Tech Publications Inc.. - 9783038350101 ; , s. 1118-1121
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Konferensbidrag (refereegranskat)abstract
- Thermal contact resistances have been measured in an experiment emulating heat transfer from a SiC die to a cooled heat sink through a heat spreader and a DBC structure. The major surface-dependent parameters are the surface roughness, surface hardness, and planarity. The measured thermal contact resistances are in agreement with theoretical values. When investigating DBC copper surfaces a second interface between the bonded Cu to AlN has to be taken into account.
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| 16. |
- Winters, Michael, 1986, et al.
(författare)
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Carrier Mobility as a Function of Temperature in as-Grown and H-intercalated Epitaxial Graphenes on 4H-SiC
- 2014
-
Ingår i: Materials Science Forum. - : Trans Tech Publications. - 1662-9752 .- 0255-5476. ; 778-780, s. 1146-1149, s. 1146-1149
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Konferensbidrag (refereegranskat)abstract
- The carrier velocity is measured as a function of electric field in as-grown and H-intercalaed epitaxial graphene grown on semi-insulating 4H-SiC in order to estimate the low field carrier mobility as a function of temperature. The mobility is also measured on the same samples as a function of temperature in a liquid Helium (He) cooled cryostat. The two temperature dependent measurements are compared in order to deduce the dominant carrier scattering mechanisms in both materials. In as-grown material, acoustic phonon scattering and impurity scattering both contribute, while impurity scattering dominates in H-intercalated material.
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| 17. |
- Xia, Jinghua, et al.
(författare)
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Characterization of LaxHfyO Gate Dielectrics in 4H-SiC MOS Capacitor
- 2014
-
Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. - 9783038350101 ; 778-780, s. 549-552
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Tidskriftsartikel (refereegranskat)abstract
- LaxHfyO nano-laminated thin film deposited using an atomic layer deposition process has been studied as a high-K gate dielectric in 4H-SiC MOS capacitors. The electrical and nano-laminated film characteristics were studied with increasing post deposition annealing (PDA) temperature in N2O ambient. The result shows that high quality LaxHfyO nano-laminated thin films with good interface and bulk qualities are fabricated using high PDA temperature.
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| 18. |
- Yen, Cheng Tyng, et al.
(författare)
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Comparative study of 4H-SiC DMOSFETs with N2O thermal oxide and deposited oxide with post oxidation anneal
- 2014
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Ingår i: Materials Science Forum. - 9783038350101 ; , s. 989-992
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Konferensbidrag (refereegranskat)abstract
- Two kinds of gate oxides, direct thermal oxidation in a nitrous oxide ambient at 1250°C (TGO) and a PECVD oxide followed by a post deposition oxidation in nitrous oxide ambient at 1150°C (DGO) were studied. DGO showed a lower interface trap density and was able to provide a higher current as being implemented in MOSFETs through the improved channel mobility. However the 6.45 MV/cm average breakdown field of DGO is lower than the 10.1 MV/cm breakdown field of TGO. The lower breakdown field, more leaky behavior and the existence of multiple breakdown mechanisms suggest that DGO needs further improvements before it can be used in real applications.
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| 19. |
- Yen, Cheng Tyng, et al.
(författare)
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SiC epi-channel lateral MOSFETs
- 2014
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Ingår i: Materials Science Forum. - 9783038350101 ; , s. 927-930
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Konferensbidrag (refereegranskat)abstract
- SiC lateral MOSFETs with multi-layered epi-channels were studied in this work. The epi-channel consisting of a high concentration n-type epilayer sandwiched between two lightly doped p-type layers showed a maximum field effect mobility of 17 cm2/V.s, as compared to 1.53 cm2/V.s for inversion type devices without epi-channels. These devices are normally-off with an average threshold voltage of 1.34V.
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