| 1. |
- Hjelm, Mats, et al.
(författare)
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Full Band Monte Carlo Study of Bulk and Surface Transport Properties in 4H and 6H-SiC
- 2001
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 184:1-4, s. 194-198
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Tidskriftsartikel (refereegranskat)abstract
- The bulk and surface electron transport properties of the 4H and 6H polytypes of silicon carbide (SiC) are studied using a full band Monte Carlo (MC) program. The model for the electrons is based on data from a full potential band structure calculation using the density functional theory (DFT) in the local density approximation (LDA). Both SiC polytypes have anisotropic transport properties, but the degree and characteristics of the anisotropy is different. In this study, we show how the anisotropy affects the bulk mobility for intermediate angles between the crystal axis and the plane perpendicular to it. Simulations of surface transport properties have also been performed for semiconductor-interface angles up to 15 degrees from the plane perpendicular to the c-axis. We present results for surface mobility and velocity as a function of the electric field component parallel to the interface plane. In the surface mobility simulations, a semi-empirical model for the semiconductor-insulator interface has been used, where it is assumed that the electrons are reflected in two perpendicular planes.
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| 2. |
- Martinez, A, et al.
(författare)
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A Monte Carlo Study of low field transport in Al doped 4H-SiC
- 2001
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 184:1-4, s. 173-177
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Tidskriftsartikel (refereegranskat)abstract
- The ohmic transport of holes in p-type aluminum-doped 4H-SiC samples is investigated using a Monte Carlo (MC) tool based on a full-potential band structure. The temperature and doping dependence of the hole mobility and its anisotropy are calculated and discussed from a physical point of view, where we stress the importance of considering two-band conduction. Acoustic and optical phonon scattering, as well as ionized and neutral impurity scattering, have been considered. The MC program considers incomplete ionization of impurity atoms, and we assume an impurity level with the ionization energy 0.2 eV, corresponding to Al-doped samples. © 2001 Published by Elsevier Science B.V
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| 3. |
- Nilsson, Hans-Erik, et al.
(författare)
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Numerical study of Bloch electron dynamics in wide band-gap semiconductors
- 2001
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 184:1-4, s. 199-203
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we are using numerical calculations to demonstrate the importance of band to band tunneling in wide band-gap semiconductors. We have considered 4H-SiC, 3C-SiC and wurtzite GaN as prototype semiconductors in the demonstration. Wide band-gap semiconductors allow device operation under very high-applied electric fields, where significant band to band tunneling is expected to occur. Hexagonal wide band-gap semiconductors have a valence band structure with a large number of bands separated by rather small energies. Our calculation shows that this leads to a very significant band to band tunneling even at relatively low electric fields. In cubic wide band-gap semiconductors the tunneling is much less pronounced. However, at the valence band maximum the band separations are small enough to allow significant band to band tunneling. The spin-orbit interaction tends to bend the band near the maximum creating degradation from a parabolic curvature. This bending is found to significantly influence the band to band tunneling process. © 2001 Elsevier Science B.V. All rights reserved.
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| 4. |
- Öhlund, Thomas, 1973-, et al.
(författare)
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Paper Surfaces for Metal Nanoparticle Inkjet Printing
- 2012
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 259, s. 731-739
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Tidskriftsartikel (refereegranskat)abstract
- The widespread usage of paper and board offer largely unexploited possibilities for printed electronics applications. Reliability and performance of printed devices on comparatively rough and inhomogenous surfaces of paper does however pose challenges.Silver nanoparticle ink has been deposited on ten various paper substrates by inkjet printing. The papers are commercially available, and selected over a range of different types and construction. A smooth nonporous polyimide film was included as a nonporous reference substrate. The substrates have been characterized in terms of porosity, absorption rate, apparent surface energy, surface roughness and material content. The electrical conductivity of the resulting printed films have been measured after drying at 60°C and again after additional sintering at 110°C. A qualitative analysis of the conductivity differences on the different substrates based on surface characterization and SEM examination is presented. Measurable parameters of importance to the final conductivity are pointed out, some of which are crucial to achieve conductivity. When certain criteria of the surfaces are met, paper media can be used as low cost, but comparably high performance substrates for metal nanoparticle inks in printed electronics applications.
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