| 1. |
- Doyle, J P, et al.
(författare)
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Observation of near-surface electrically active defects in n-type 6H-SiC
- 1998
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 83, s. 3649-3651
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Tidskriftsartikel (refereegranskat)abstract
- In n-type 6H-SiC epitaxial layers grown by vapor phase epitaxy, we find that in contrast to the majority of the epitaxial layer, where electrically active defects are observed with a concentration less than 1 X 10(-13) cm(-3), a region near the front surface contains defects with concentrations approaching 10(14) cm(-3). A relationship between the near-surface defects and metallic impurities is suggested by a Ti concentration of 1 X 10(16) cm(-3) in this region. The high concentration of near surface defects is found to significantly reduce the carrier lifetime. (C) 1998 American Institute of Physics. [S0021-8979(98)03007-2].
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| 2. |
- Esteve, Romain, et al.
(författare)
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Advanced oxidation process combining oxide deposition and short postoxidation step for N-type 3C- and 4H-SiC
- 2009
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 106:4
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Tidskriftsartikel (refereegranskat)abstract
- The electrical properties of oxides fabricated on n-type 3C-SiC (001) and 4H-SiC (0001) epilayers using an advanced oxidation process combining plasma enhanced deposition and rapid postoxidation steps have been investigated. Three gas atmospheres have been studied for the postoxidation steps: N2O, dry, and wet oxygen (H2O). In comparison, additional oxides using postannealing in pure N-2 have been fabricated. The implementation of wet oxygen resulted. in a significant decrease in the interface traps density, in a reduction of oxide fixed charges and in the increased breakdown field in the case of 3C-SiC. In the case of 4H-SiC the postoxidation in N2O is a superior postprocessing step.
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| 3. |
- Esteve, Romain, et al.
(författare)
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Comparative study of thermally grown oxides on n-type free standing 3C-SiC (001)
- 2009
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 106:4
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Tidskriftsartikel (refereegranskat)abstract
- Alternative ways to improve the oxidation process of free standing 3C-SiC (001) are developed and tested with the aim to reduce the fixed and mobile charges in the oxide and at the SiO2/3C-SiC interface. The postoxidation annealing step in wet oxygen (O-2+H-2) is demonstrated to be beneficial for n-type 3C-SiC metal-oxide-semi conductor capacitors resulting in significant reduction in flat band voltage shift, effective oxide charge density, and density of interface traps. The inefficiency of nitridation for the improvement of the oxide quality on 3C-SiC is discussed.
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| 4. |
- Esteve, Romain, et al.
(författare)
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Electrical properties of MOS structures based on 3C-SiC(111) epilayers grown by Vapor-Liquid-Solid Transport and Chemical-Vapor Deposition on 6H-SiC(0001)
- 2010
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Ingår i: AIP Conference Proceedings. - : AIP Publishing. - 9780735408470 ; , s. 55-58
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Konferensbidrag (refereegranskat)abstract
- The electrical properties of post-oxidized PECVD oxides in wet oxygen based on 3C-SiC(111) epilayers grown by Vapor-Liquid-Solid and Chemical-Vapor-Deposition mechanisms on 6H-SiC(0001) have been studied. Different 6H-SiC(0001) samples exhibiting diverse crystal orientations (on-axis, 2 degrees off-axis) and growth conditions were regarded. A comparative study of oxide qualities has been carried out via capacitance and conductance measurements (C-G-V). Achieved interface traps densities and effective oxide charges were compared for the different samples. Reliability issues have been considered via current measurements (I-V and TZDB) and statistical data treatment techniques (Weibull plots). Oxides based on 3C-SiC layer grown by a process combining VLS and CVD methods demonstrated low interface states densities D-it of 1.2 x 10(10) eV(-1)cm(-2) at 0.63 eV below the conduction band and fixed oxide charges Q(eff)/(g) estimated to -0.1 x 10(11) cm(-2)
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| 5. |
- Ghandi, Reza, et al.
(författare)
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Experimental evaluation of different passivation layers on the performance of 3kV 4H-SiC BJTs
- 2010
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Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 645-648:Part 1-2, s. 661-664
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the electrical performance in terms of maximum current gain, ON-resistance and blocking capability has been compared for 4H-SiC BJTs passivated with different surface passivation layers. Variation in BJT performance has been correlated to densities of interface traps and fixed oxide charge, as evaluated through MOS capacitors. Six different methods were used to fabricate SiO2 surface passivation on BJT samples from the same wafer. The highest current gain was obtained for PECVD deposited SiO2 which was annealed in N2O ambient at 1100 degrees C during 3 hours. Variations in breakdown voltage for different surface passivations were also found, and this is attributed to differences in fixed oxide charge that can affect the optimum dose of the high voltage JTE termination.
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| 6. |
- Nordell, Nils, et al.
(författare)
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Boron implantation and epitaxial regrowth studies of 6H SiC
- 1998
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Ingår i: Journal of Electronic Materials. - : Springer Science and Business Media LLC. - 0361-5235 .- 1543-186X. ; 27:7, s. 833-837
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Tidskriftsartikel (refereegranskat)abstract
- Implantation of B has been performed into an epitaxially grown layer of 6H SiC, at two different B concentrations, 2 x 10(16) cm(-3) and 2 x 10(18) cm(-3). Subsequently, an epitaxial layer was regrown on the B implanted layer. The samples were investigated by transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS). In the highly B-doped layers plate-like defects were found, associated with large strain fields, and an increased B concentration. These defects were stable at the originally implanted region during regrowth and at anneal temperatures up to 1700 degrees C. In the samples implanted with the lower B concentration, no crystal defects could be detected by TEM. No threading dislocations or other defects were observed in the regrown epitaxial layer, which shows the possibility to grow a layer with high crystalline quality on B implanted 6H SiC. By SIMS, it was found that B piles up at the interface to the regrown layer, which could be explained by enhanced diffusion from an increased concentration of point defects created by implantation damage in the region. B is also spread out into the original crystal and in the regrown layer at a concentration of below 2 x 10(16) cm(-3), with a diffusion constant estimated to 1.3 x 10(-12) cm(2)s(-1). This diffusion is most probably not driven by implantation damage, but by intrinsic defects in the grown crystal. Our investigation shows that the combination of implantation and subsequent regrowth techniques could be used in SiC for building advanced device structures, with the crystal quality in the regrown layer not being deteriorated by crystal defects in the implanted region. A device process using B implantation and subsequent regrowth could on the other hand be limited by the diffusion of B.
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| 7. |
- Bakowski, Mietek, et al.
(författare)
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Design and characterization of newly developed 10 kV 2 A SiC p-i-n diode for soft-switching industrial power supply
- 2015
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Ingår i: IEEE Transactions on Electron Devices. - : Institute of Electrical and Electronics Engineers Inc.. - 0018-9383 .- 1557-9646. ; 62:2, s. 366-373
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Tidskriftsartikel (refereegranskat)abstract
- 10 kV, 2 A SiC p-i-n diodes have been designed and fabricated. The devices feature excellent stability of forward characteristics and robust junction termination with avalanche capability of 1 J. The fabricated diodes have been electrically evaluated with respect to dynamic ON-state voltage, reverse recovery behavior, bipolar stability, and avalanche capability. More than 60% reduction of losses has been demonstrated using newly developed 10-kV p-i-n diodes in a multikilowatt high voltage, high-frequency dc/dc soft-switching converter
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| 8. |
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| 9. |
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| 10. |
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| 11. |
- Danielsson, Erik, et al.
(författare)
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A 4H-SiC BJT with an epitaxially regrown extrinsic base layer
- 2005
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Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 483, s. 905-908
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Tidskriftsartikel (refereegranskat)abstract
- 4H-SiC BJTs were fabricated using epitaxial regrowth instead of ion implantation to form a highly doped extrinsic base layer necessary for a good base ohmic contact. A remaining p(+) regrowth spacer at the edge of the base-emitter junction is proposed to explain a low current gain of 6 for the BJTs. A breakdown voltage of 1000 V was obtained for devices with Al implanted JTE.
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| 12. |
- Domeij, Martin, et al.
(författare)
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Current gain dependence on emitter width in 4H-SiC BJTs
- 2006
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Ingår i: Materials Science Forum. - : Trans Tech Publications Inc.. - 0255-5476 .- 1662-9752. - 9780878494255 ; 527-529, s. 1425-1428
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports the fabrication of epitaxial 4H-SiC bipolar junction transistors (BJTs) with a maximum current gain beta = 64 and a breakdown voltage of 1100 V. The high beta value is attributed to high material quality obtained after a continuous epitaxial growth of the base-emitter junction. The current gain of the BJTs increases with increasing emitter width indicating a significant influence of surface recombination. This "emitter-size" effect is in good agreement with device simulations including recombination in interface states at the etched termination of the base-emitter junction.
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| 13. |
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| 14. |
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| 15. |
- Galeckas, Augustinas, et al.
(författare)
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Investigation of structural stability in 4H-SiC structures with heavy ion implanted interface
- 2006
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Ingår i: Silicon Carbide and Related Materials 2005, Pts 1 and 2. - 9780878494255 ; , s. 395-398
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Konferensbidrag (refereegranskat)abstract
- We investigate the possibility of controlling formation of stacking faults (SFs) at the interface region by implanting the 4H-SiC substrate with low-energy antimony ions (75 keV Sb+) prior to conventional CVD growth of the homoepitaxial layers. This approach is based on the solidsolution hardening concept, according to which interaction of impurity atoms with dislocations makes the motion of the latter more difficult. Photoluminescence imaging spectroscopy is employed to investigate incorporation of Sb+ implants at the buried interface and also to assess its impact on structural degradation. Spectral results are analyzed considering both the onset of n-type doping and irradiation damage. The latter factor was estimated separately from supplementary measurements of high-energy (2.5 MeV H+) proton-irradiated 4H-SiC epilayers. We compare results of optically stimulated SF formation in virgin and Sb implanted regions and provide a comprehensive picture of the defect evolution, including microscopic details of the imminent nucleation sites.
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| 16. |
- Ghandi, Reza, et al.
(författare)
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Surface-passivation effects on the performance of 4H-SiC BJTs
- 2011
-
Ingår i: IEEE Transactions on Electron Devices. - 0018-9383 .- 1557-9646. ; 58, s. 259-265
-
Tidskriftsartikel (refereegranskat)abstract
- In this brief, the electrical performance in terms of maximum current gain and breakdown voltage is compared experimentally and by device simulation for 4H-SiC BJTs passivated with different surface-passivation layers. Variation in bipolar junction transistor (BJT) performance has been correlated to densities of interface traps and fixed oxide charge, as evaluated through MOS capacitors. Six different methods were used to fabricate SiO2 surface passivation on BJT samples from the same wafer. The highest current gain was obtained for plasma-deposited SiO2 which was annealed in N2O ambient at 1100 °C for 3 h. Variations in breakdown voltage for different surface passivations were also found, and this was attributed to differences in fixed oxide charge that can affect the optimum dose of the high-voltage junction-termination extension (JTE). The dependence of breakdown voltage on the dose was also evaluated through nonimplanted BJTs with etched JTE.
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| 17. |
- Linnarsson, M K, et al.
(författare)
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Aluminum and boron diffusion in 4H-SiC
- 2003
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Ingår i: SILICON CARBIDE 2002-MATERIALS, PROCESSING AND DEVICES. ; , s. 291-301
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Konferensbidrag (refereegranskat)abstract
- A brief survey is given of some recent result of boron diffusion in low doped n-type (intrinsic) and p-type 4H-SiC. Aluminum diffusion and solubility limit in 4H-SiC are also discussed. Ion implantation of boron has been performed in epitaxial material to form a diffusion source but also epitaxial 4H-SiC structures, with heavily boron or aluminum doped layers prepared by vapor phase epitaxy have been studied. Heat treatments have been made at temperatures ranging from 1100 to 2050degreesC for 5 minutes up to 64 h. Secondary ion mass spectrometry has been utilized for analysis. For boron diffusion in acceptor doped 4H-SiC, 4x10(19) Al atoms/cm(3), an activation energy of 5.3 eV has been determined and a strong dependence on Al content for the diffusion coefficient is revealed. Transient enhanced diffusion of ion-implanted boron in intrinsic 4H-SiC samples is discussed. Solubility limits of similar to1x10(20) Al/cm(3) (1700degreesC) and <1x10(20) B/cm(3) (1900degreesC) have been deduced.
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| 18. |
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| 19. |
- Linnarsson, M K, et al.
(författare)
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Deuterium incorporation in acceptor doped epitaxial layers of 6H-SiC
- 1998
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Ingår i: SILICON CARBIDE, III-NITRIDES AND RELATED MATERIALS, PTS 1 AND 2. ; , s. 761-764
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Konferensbidrag (refereegranskat)abstract
- Deuterium is introduced in boron doped epitaxial layers of 6H-SiC by implantation of 30 keV H-2(+) ions in order to form a diffusion source. The samples were subsequently annealed in vacuum at 700 degrees C/16h, 800 degrees C/4h and 900 degrees C/4h. Using depth profiling by secondary ion mass spectrometry (SIMS), the distributions of deuterium at different levels of boron doping are studied. The deuterium concentration correlates with the boron concentration and at a level of similar to 10(18) cm(-3) a ratio H-2/B-11 larger than 0.5 is obtained. From capacitance-voltage (CV) measurements a decrease in the electrical carrier concentration by 50% is revealed after deuterium diffusion at 800 degrees C/4h. At 900 degrees C passivation of the boron accepters ceases but the H-2 atoms are still confined to the boron-doped regions and display no long range migration.
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| 20. |
- Linnarsson, M K, et al.
(författare)
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Diffusion of light elements in 4H-and 6H-SiC
- 1999
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Ingår i: Materials Science & Engineering. - 0921-5107 .- 1873-4944. ; 61-2, s. 275-280
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Tidskriftsartikel (refereegranskat)abstract
- Deuterium and lithium were introduced in p-type SiC by implantation of 20 keV H-2(+) or 30 keV Li-7(+) ions in order to form a diffusion source. The samples were subsequently annealed in vacuum in the temperature range 400-700 degrees C for 0.25 to 16 h. Secondary ion mass spectrometry (SIMS) was used to measure the deuterium and the lithium distribution after heat treatments. Both deuterium and lithium readily decorate the bombardment-induced defects in the vicinity of the ion implantation profile and they are also trapped, most likely by residual boron impurities, during diffusion into the bulk. An effective diffusion coefficient, reflecting the dissociation of trapped lithium, with an activation energy of 2.1 eV is extracted for lithium diffusion in p-type 6H SIG. Furthermore, a capture radius for trapping (most likely by boron) of deuterium is estimated as 10 Angstrom. (C) 1999 Elsevier Science S.A. All rights reserved.
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| 21. |
- Linnarsson, Margareta K., et al.
(författare)
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Formation of precipitates in heavily boron doped 4H-SiC
- 2006
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 252:15, s. 5316-5320
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Tidskriftsartikel (refereegranskat)abstract
- Secondary ion mass spectrometry (SIMS) and transmission electron microscopy (TEM) are utilized to study precipitation and the solubility of B in 4H-SiC epitaxial layers super saturated with B. Heat treatments are performed in Ar atmosphere in an rf-heated furnace at temperatures between 1700 and 2000 degrees C. SIMS ion images, and TEM micrographs reveal the formation of two types of precipitates where the larger, more thermally stable one is suggested to be B4C. The boron solubility is determined from SIMS depth profiles and is shown to follow the Arrhenius expression: 7.1 x 10(22) exp(-1.4 eV/k(B)T) cm(-3) over the studied temperature range.
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| 22. |
- Linnarsson, M K, et al.
(författare)
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Metal-contact enhanced incorporation of deuterium in 4H-and 6H-SiC
- 2000
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Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 338-3, s. 937-940, s. 937-940
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Tidskriftsartikel (refereegranskat)abstract
- Deuterium was introduced in p-type SiC from a gas ambient. The samples were partially coated with 200 Angstrom thick metal layer of titanium, nickel, platinum or gold. Heat treatments were performed in the temperature range 500-800 degreesC during 4 h. Secondary ion mass spectrometry (SIMS) was used to measure the deuterium content after deuterium exposure. The catalytic metal coating is shown to play an important role for introducing deuterium into SiC. Nickel and platinum facilitate hydrogen incorporation in p-type SiC, which may be due to an increased hydrogen concentration at the metal/SiC interface and/or an increase the H+ ions to H ratio. No in-diffusion of deuterium is observed using titanium although large quantities of deuterium are stored in the titanium film. Furthermore, gold reveals an inert character and does not promote in-diffusion of deuterium.
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| 23. |
- Linnarsson, Margareta K., et al.
(författare)
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Solubility limit and precipitate formation in Al-doped 4H-SiC epitaxial material
- 2001
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 79:13, s. 2016-2018
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Tidskriftsartikel (refereegranskat)abstract
- Heavily Al-doped 4H-SiC structures have been prepared by vapor phase epitaxy. Subsequent anneals have been carried out in an Ar atmosphere in a rf-heated furnace between 1500 degreesC and 2000 degreesC for 0.5 to 3 h. Secondary ion mass spectrometry has been utilized to obtain Al concentration versus depth as well as lateral distributions (ion images). Transmission electron microscopy (TEM) has been employed to study the crystallinity and determine phase composition after heat treatment. A solubility limit of similar to 2x10(20) Al/cm(3) (1900 degreesC) is extracted. Three-dimensional ion images show that the Al distribution does not remain homogeneous in layers heat treated at 1700 degreesC or above when the Al concentration exceeds 2x10(20) cm(-3). Al-containing precipitates are identified by energy-filtered TEM.
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| 24. |
- Linnarsson, Margareta K., et al.
(författare)
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Solubility limits of dopants in 4H-SiC
- 2003
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 203, s. 427-432
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial 4H-SiC structures with heavily boron or aluminium doped layers have been prepared by vapour phase epitaxy. The samples have been annealed in Ar atmosphere in an RF-heated furnace between 1700 and 2000 degreesC for 45 min to 64 h. Secondary ion mass spectrometry has been employed to obtain depth distributions as well as lateral distributions (ion imaging) for boron and aluminium. Transmission electron microscopy has been used to study the crystallinity and determine phase composition. Solubility limits of similar to 1 x 10(20) Al/cm(3) (1700 degreesC) and < 1 x 10(20) B/cm(3) (1900 degreesC) have been deduced.
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| 25. |
- Lorenzzi, Jean, et al.
(författare)
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3C-SiC MOS based devices : from material growth to device characterization
- 2011
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Ingår i: Silicon carbide and related materials 2010. - : Trans Tech Publications, Ltd.. ; , s. 433-
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Konferensbidrag (refereegranskat)abstract
- In this work we report on the growth and preparation of 3C-SiC(111) material for metal-oxide-semiconductor (MOS) application. In order to achieve reasonable material quality to prepare MOS capacitors several and crucial steps are needed: 1) heteroepitaxial growth of high quality 3C-SiC(111) layer by vapour-liquid-solid mechanism on 6H-SiC(0001) substrate, 2) surface polishing, 3) homoepitaxial re-growth by chemical vapour deposition and 4) use of an advanced oxidation process combining plasma enhanced chemical vapour deposition (PECVD) SiO2 and short post-oxidation steps in wet oxygen. Combining all these processes the interface traps density (D-it)can be drastically decreased down to 1.2 x 10(10) eV(-1)cm(-2) at 0.63 eV below the conduction band. To our knowledge, these values are the best ever reported for SiC material in general and 3C-SiC in particular.
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| 26. |
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| 27. |
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| 28. |
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| 29. |
- Schoner, A., et al.
(författare)
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Dependence of the aluminium ionization energy on doping concentration and compensation in 6H-SiC
- 1996
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Ingår i: Silicon Carbide and Related Materials1995. - : Institute of Physics Publishing (IOPP). - 0750303352 ; , s. 493-496
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Konferensbidrag (refereegranskat)abstract
- Hall-effect measurements on aluminium (Al)-doped p-type 6H-SiC were made and the dependence of the Al ionization energy on doping concentration and compensation was investigated. It is shown that the Al ionization energy is almost constant for a degree of compensation K much less than 0.01 up to an Al concentration of 5 . 10(20)cm(-3). An average value for the Al ionization energy is found to be 241.6 +/- 5.2 meV. Additionally, we find that the Al ionization energy for a degree of compensation in a range of 0.01 to 0.5 varies with doping concentration and compensation. An impurity band model describing this dependence is discussed.
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| 30. |
- Schoner, A, et al.
(författare)
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Hall effect investigations of 4H-SiC epitaxial layers grown on semi-insulating and conducting substrates
- 1999
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Ingår i: Materials Science & Engineering. - 0921-5107 .- 1873-4944. ; 61-2, s. 389-394
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen- and aluminum-doped 4H silicon carbide epitaxial layers were grown simultaneously on semi-insulating and conducting substrates. The layers were investigated by conventional van der Pauw Hall effect measurements and for comparison also with secondary ion mass spectrometry and capacitance voltage measurements. It was found, that the carrier concentration in the layers grown on conducting substrates were overestimated by the Hall effect measurement, which leads to an underestimation of the ionization energy of the main dopant, as compared to the layer grown on semi-insulating substrates. The difference can be explained by a two-layer Hall effect model. (C) 1999 Elsevier Science S.A. All rights reserved.
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| 31. |
- Schoner, A, et al.
(författare)
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Hydrogen incorporation in epitaxial layers of 4H- and 6H-silicon carbide grown by vapor-phase epitaxy
- 1997
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Ingår i: Diamond and related materials. - 0925-9635 .- 1879-0062. ; 6, s. 1293-1296
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Tidskriftsartikel (refereegranskat)abstract
- The incorporation of hydrogen during vapor phase epitaxy was investigated using secondary ion mass spectroscopy, low temperature photoluminescence, and capacitance-voltage measurements. It was found that hydrogen incorporation is strongly dependent on the concentration of the acceptor dopants aluminum and boron, regardless of changes in the doping concentration caused by varying the concentration ratio between carbon and silicon or the dopant precursor flow. An electrical passivation of the acceptor dopants was found and could be reduced by annealing at temperatures above 1000 degrees C. At the same anneal temperature hydrogen-related photoluminescence was considerably reduced and the diffusion of hydrogen was detected. (C) 1997 Elsevier Science S.A.
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| 32. |
- Tobias, Peter, et al.
(författare)
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Studies of the ambient dependent inversion capacitance of catalytic metal oxide silicon carbide devices based on 6H- and 4H-SiC material
- 1998
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Ingår i: Silicon Carbide, III-Nitrides and Related Materials, Part 1-2. - : Trans Tech Publications. - 0878497900 ; , s. 1089-1092
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Konferensbidrag (refereegranskat)abstract
- Platinum-oxide-silicon carbide structures change their capacitance upon gas exposure and are used as gas sensors. The decrease of the inversion capacitance within 750 to 900 degrees C due to hydrogen exposure is studied for 4H- and 6H-SiC,:both n- and p-type. A mechanism for the capacitance decrease is suggested which explains also the large change in the conductance of the structures.
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