| 1. |
- Ayedh, H. M., et al.
(författare)
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Kinetics modeling of the carbon vacancy thermal equilibration in 4H-SiC
- 2018
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Ingår i: International Conference on Silicon Carbide and Related Materials, ICSCRM 2017. - : Trans Tech Publications. - 9783035711455 ; , s. 233-236
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Konferensbidrag (refereegranskat)abstract
- The carbon vacancy (VC) is a major limiting-defect of minority carrier lifetime in n-type 4H-SiC epitaxial layers and it is readily formed during high temperature processing. In this study, a kinetics model is put forward to address the thermodynamic equilibration of VC, elucidating the possible atomistic mechanisms that control the VC equilibration under C-rich conditions. Frenkel pair generation, injection of carbon interstitials (Ci’s) from the C-rich surface, followed by recombination with VC’s, and diffusion of VC’s towards the surface appear to be the major mechanisms involved. The modelling results show a close agreement with experimental deep-level transient spectroscopy (DLTS) depth profiles of VC after annealing at different temperatures.
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| 2. |
- Ekström, Mattias, et al.
(författare)
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Low temperature Ni-Al ohmic contacts to p-TYPE 4H-SiC using semi-salicide processing
- 2018
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Ingår i: International Conference on Silicon Carbide and Related Materials, ICSCRM 2017. - : Trans Tech Publications. - 9783035711455 ; , s. 389-392
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Konferensbidrag (refereegranskat)abstract
- Most semiconductor devices require low-resistance ohmic contact to p-type doped regions. In this work, we present a semi-salicide process that forms low-resistance contacts (~10-4 Ω cm2) to epitaxially grown p-type (>5×1018 cm-3) 4H-SiC at temperatures as low as 600 °C using rapid thermal processing (RTP). The first step is to self-align the nickel silicide (Ni2Si) at 600 °C. The second step is to deposit aluminium on top of the silicide, pattern it and then perform a second annealing step in the range 500 °C to 700 °C.
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| 3. |
- Galeckas, A., et al.
(författare)
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Optical and microstructural investigation of heavy B-doping effects in sublimation-grown 3C-SiC
- 2018
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Ingår i: Materials Science Forum. - : Trans Tech Publications Ltd. - 9783035711455 ; , s. 221-224
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Konferensbidrag (refereegranskat)abstract
- In this work, a complementary microstructural and optical approach is used to define processing conditions favorable for the formation of deep boron-related acceptor centers that may provide a pathway for achieving an intermediate band behavior in highly B-doped 3C-SiC. The crystallinity, boron solubility and precipitation mechanisms in sublimation-grown 3C-SiC crystals implanted to 1-3 at.% B concentrations were investigated by STEM. The revealed defect formation and boron precipitation trends upon thermal treatment in the range 1100-2000oC have been crosscorrelated with the optical characterization results provided by imaging PL spectroscopy. We discuss optical activity of the implanted B ions in terms of both shallow acceptors and deep D-centers, a complex formed by a boron atom and a carbon vacancy, and associate the observed spectral developments upon annealing with the strong temperature dependence of the D-center formation efficiency, which is further enhanced by the presence of implantation-induced defects. © 2018 Trans Tech Publications, Switzerland.
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| 4. |
- Hallén, Anders, et al.
(författare)
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Radiation hardness for silicon oxide and aluminum oxide on 4H-SiC
- 2018
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Ingår i: International Conference on Silicon Carbide and Related Materials, ICSCRM 2017. - : Trans Tech Publications Inc.. - 9783035711455 ; , s. 229-232
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Konferensbidrag (refereegranskat)abstract
- The radiation hardness of two dielectrics, SiO2 and Al2O3, deposited on low doped, ntype 4H-SiC epitaxial layers has been investigated by exposing MOS structures involving these materials to MeV proton irradiation. The samples are examined by capacitance voltage (CV) measurements and, from the flat band voltage shift, it is concluded that positive charge is induced in the exposed structures detectable for fluence above 1×1011 cm-2. The positive charge increases with proton fluence, but the SiO2/4H-SiC structures are slightly more sensitive, showing that Al2O3 can provide a more radiation hard passivation, or gate dielectric for 4H-SiC devices.
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| 5. |
- Kajihara, J., et al.
(författare)
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4H-SiC pMOSFETs with al-doped S/D and NbNi silicide ohmic contacts
- 2018
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Ingår i: International Conference on Silicon Carbide and Related Materials, ICSCRM 2017. - : Trans Tech Publications. - 9783035711455 ; , s. 423-427
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Konferensbidrag (refereegranskat)abstract
- 4H-SiC pMOSFETs with Al-doped S/D and NbNi silicide ohmic contacts were demonstrated and were characterized at up to a temperature of 200°C. For the pMOSFETs, silicides on p-type 4H-SiC with Nb/Ni stack, Nb-Ni Alloy, Ni and Nb/Ti were investigated, and the Nb/Ni stack silicide with the contact resistance of 5.04×10-3 Ωcm2 were applied for the pMOSFETs.
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| 6. |
- Kurose, T., et al.
(författare)
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Low-parasitic-capacitance self-aligned 4H-SiC nMOSFETs for harsh environment electronics
- 2018
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Ingår i: Materials Science Forum. - : Trans Tech Publications. - 0255-5476 .- 1662-9752. - 9783035711455 ; 924, s. 971-974
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Tidskriftsartikel (refereegranskat)abstract
- Low-parasitic-capacitance 4H-SiC nMOSFETs using a novel self-aligned process were suggested and demonstrated. In these nMOSFETs, device characteristics including parasitic capacitances (gate-source, gate-drain, drain-source capacitance) were investigated and low parasitic capacitance was achieved by the self-aligned structure
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| 7. |
- Linnarsson, Margareta K., et al.
(författare)
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Surface erosion of ion-implanted 4H-SiC during annealing with carbon cap
- 2018
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Ingår i: International Conference on Silicon Carbide and Related Materials, ICSCRM 2017. - : Trans Tech Publications Inc.. - 9783035711455 ; , s. 373-376
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Konferensbidrag (refereegranskat)abstract
- The stability/ erosion of the interface between a C-cap and 4H-SiC have been studied by secondary ion mass spectrometry (SIMS). Aluminum implantation has been used to monitor the position of the moving interface as well as to investigate the influence on the interface stability by the crystal quality of the 4H-SiC. After Al implantation a C-cap has been deposited by pyrolysis of photoresist. Subsequent annealing has been performed at 1900 and 2000 °C with durations between 15 minutes and 1 hour. SIMS measurements have been performed without removal of the C-cap. The surface remains smooth after the heat treatment, but a large amount of SiC material from the uppermost part of the wafer is lost. The amount of lost material is related to for instance annealing temperature, ambient conditions and ion induced crystal damage. This contribution gives a brief account of the processes governing the SiC surface decomposition during C-cap post implant annealing.
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| 8. |
- Salemi, Arash, et al.
(författare)
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Conductivity modulated and implantation-free 4H-SiC ultra-high-voltage PiN Diodes
- 2018
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Ingår i: International Conference on Silicon Carbide and Related Materials, ICSCRM 2017. - : Trans Tech Publications Inc.. - 9783035711455 ; , s. 568-572
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Konferensbidrag (refereegranskat)abstract
- Implantation-free mesa etched ultra-high-voltage 4H-SiC PiN diodes are fabricated, measured and analyzed by device simulation. The diode’s design allows a high breakdown voltage of about 19.3 kV according to simulations. No reverse breakdown is observed up to 13 kV with a very low leakage current of 0.1 μA. A forward voltage drop (VF) and differential on-resistance (Diff. Ron) of 9.1 V and 41.4 mΩ cm2 are measured at 100 A/cm2, respectively, indicating the effect of conductivity modulation.
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| 9. |
- Shakir, Muhammad, et al.
(författare)
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Electrical characterization of integrated 2-input TTL NAND Gate at elevated temperature, fabricated in bipolar SiC-technology
- 2018
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Ingår i: International Conference on Silicon Carbide and Related Materials, ICSCRM 2017. - : Trans Tech Publications Inc.. - 9783035711455 ; , s. 958-961
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Konferensbidrag (refereegranskat)abstract
- This work presents the design and electrical characterization of in-house-fabricated 2-input NAND gate. The monolithic bipolar 2-input NAND gate employing transistor-transistor logic (TTL) is demonstrated in 4H-SiC and operates over a wide range of temperature and supply voltage. The fabricated circuit was characterized on the wafer by using a hot-chuck probe-station from 25 °C up to 500 °C. The circuit is also characterized over a wide range of voltage supply i.e. 11 to 20 V. The output-noise margin high (NMH) and output-noise margin low (NML) are also measured over a wide range of temperatures and supply voltages using voltage transfer characteristics (VTC). The transient response was measured by applying two square waves of, 5 kHz and 10 kHz. It is demonstrated that the dynamic parameters of the circuit are temperature dependent. The 2-input TTL NAND gate consumes 20 mW at 500 °C and 15 V.
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