| 1. |
- Ahuja, R., et al.
(författare)
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Optical properties of 4H-SiC
- 2002
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Ingår i: J. Appl. Phys.. ; 91:4, s. 2099-2103
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Bakker, Jimmy W. P., et al.
(författare)
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Improvement of porous silicon based gas sensors by polymer modification
- 2003
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Ingår i: Physica Status Solidi (A). - : Wiley. - 0031-8965 .- 1521-396X. ; 197:2, s. 378-381
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Tidskriftsartikel (refereegranskat)abstract
- Gas sensing was performed using spectroscopic ellipsometry and porous silicon films. Modification of the porous layer by polymer deposition showed an increase in sensitivity to organic solvent vapor of up to 135%. The increase in sensitivity is strongly dependent on polymer concentration. At high concentrations, too much polymer is deposited, presumably blocking the pores, causing a decrease in sensitivity. At sufficiently low concentrations, the polymer causes a strong increase in sensitivity. This is assumed to be caused by the polymer being deposited inside the pores, where its interaction with the vapor influences the sensitivity. At very low concentration, the sensitivity approaches values obtained without polymer modification. The sensitivity increase is different for different vapors, pointing to possible selectivity enhancement.
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| 3. |
- de Oliveira, A. C., et al.
(författare)
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Spectroscopy studies of 4H-SiC
- 2002
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Ingår i: Materials Research. ; 6, s. 43-
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Tidskriftsartikel (refereegranskat)
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| 4. |
- Edwards, NV, et al.
(författare)
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Real-time assessment of overlayer removal on 4H-SiC surfaces : Techniques and relevance to contact formation
- 2000
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Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 338-3, s. 1033-1036
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Tidskriftsartikel (refereegranskat)abstract
- We applied real-time spectroscopic ellipsometric (SE) measurements to assess the removal of overlayer material from 4H-SiC Si- and C-face surfaces in order to investigate the final step of an otherwise standard RCA cleaning regimen commonly used to prepare SiC surfaces for contact formation. The selected treatments (buffered hydrofluoric acid (HF), concentrated HF, dilute HF and 5% HF in Methanol) removed 4 to 40 Angstrom of effective SiO2 overlayer thickness from these surfaces. We also found that the concentrated HF treatment yielded the best surface, i.e. the most abrupt bulk-to-ambient transition region.
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| 5. |
- Edwards, NV, et al.
(författare)
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Real-time assessment of selected surface preparation regimens for 4H-SiC surfaces using spectroscopic ellipsometry
- 2000
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Ingår i: Surface Science. - : Elsevier. - 0039-6028 .- 1879-2758. ; 464:1, s. L703-L707
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Tidskriftsartikel (refereegranskat)abstract
- Spectroscopic ellipsometry (SE) was used to assess the removal of overlayer material from 4H-SiC (0001) and (0001) [Si- and C-face] surfaces in real time and, in particular, the critical final step of an otherwise standard RCA cleaning regimen commonly used to prepare SiC surfaces for contact formation. The treatments selected [buffered hydrofluoric acid (HF), concentrated HF, and dilute HF] removed 4-40 Angstrom of effective SiO2 overlayer thickness from these surfaces. The concentrated HF treatment yielded the best surface, i.e. that with the most abrupt transition region between bulk and surface and with the most oxide material removed. A fourth treatment regimen (sequential application of methanol, water, and 5% HF in methanol) was also developed for comparison with the full RCA clean. (C) 2000 Elsevier Science B.V. All rights reserved.
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| 6. |
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| 7. |
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| 8. |
- Veszelei, Monica, et al.
(författare)
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Optical constants and Drude analysis of sputtered zirconium nitride films
- 1994
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Ingår i: Applied Optics. - 0003-6935 .- 1539-4522. ; 33:10, s. 1993-2001
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Tidskriftsartikel (refereegranskat)abstract
- Opaque and semitransparent dc magnetron-sputtered ZrN films on glass and silicon have been optically characterized with spectral reflectance measurements and ellipsometry. High rate sputtered ZrN has good optical selectivity, i.e., higher than 90% infrared reflectance and a pronounced reflectance step in the visible to a reflectance minimum of less than 10% at 350 nm. The results are comparable with those obtained for single crystalline samples and those prepared by chemical vapor deposition. The complex optical constant (N = n v ik) for opaque films has been determined in the 0.23-25-µm wavelength range with Kramers-Kronig integration of bulk reflectance combined with oblique incidence reflectance for p-polarized light. A variable angle of incidence spectroscopic ellipsometer has been used for determination of the optical constants in the 0.28-1.0-µm wavelength region. The results of the two methods show excellent agreement. The results indicate that ZrN is free electronlike and the Drude model can be applied. The best opaque films had Drude plasma energies (ħω(p) between 6.6 and 7.5 eV and relaxation energies (ħ/τ) between 0.29 and 0.36 eV. Ellipsometer data for the semitransparent films show that the refractive index (n) in the visible increases with decreasing film thickness whereas the extinction coefficient (k) is essentially unchanged. The optical properties are improved by deposition upon a heated substrate.
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