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Abstract Carbon-doped silicon oxide (CDO) thin films as low dielectric constant materials were deposited on both n-type silicon (Si) (100) and indium tin oxide coated polyethylene naphthalate (ITO/PEN) substrates, using the plasma-enhanced chemical vapor deposition of tetrakis(trimethylsilyoxy)silane (TTMSS) precursor. Chemical structures of the CDO films were analyzed by using FTIR (Fourier transformation infrared) spectroscopy and XPS (X-ray photoelectron spectroscopy). The chemical bonds related with hydrocarbon and Si–O were the main characteristics of the CDO films. The prominent peaks from the FTIR spectra included Si–O–Si stretching, Si–CH3 bending, Si–(CH3)x stretching, and CHx stretching modes. XPS spectra composed of the O1s, C1s, and Si2p electron orbitals were used to quantitatively analyze the elemental composition of the CDO films. The growth mechanisms of CDO films were dependent on the substrate type. For the ITO/PEN substrate, the lack of Si atoms on the ITO surface made difficulty in forming initial Si–O bonds, resulting in insufficient Si–O–Si structure. In comparison, the CDO films could grow easily on Si substrates due to pre-existing Si–O bonds on the surface. The chemical structures of the CDO films are expected to affect electrical and mechanical performances.
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Optimizing noncontact oxygen‐plasma treatment to improve the performance of a top‐down nanofabricated surface enhanced Raman spectroscopy substrate with structurally responsive, high‐aspect‐ratio nanopillar array
Abstract Our use of a commercially available monolithic surface enhanced Raman spectroscopy substrate based on metallized arrays of nanopillars has been hindered by the structured and variable background spectrum found in as‐supplied substrates. We identify surface contamination—at minimum from the shipping container—as the root cause of the variability and observed that our cleaning protocol could enhance the spectral performance but could also significantly degrade it in some cases. These uniquely nanostructured substrates offer on‐demand hot spot formation by solvent‐evaporation‐induced nanopillar leaning, so that oxygen‐plasma treatment was used as a noncontact method to preserve this capability. Suitable plasma cleaning conditions produced less structured background spectra and yielded higher signal intensities. Detrimental plasma power and exposure durations could yield significantly cleaner background spectra but at the significant cost of response to analyte. Scanning electron micrographs showed the plasma could alter the surface morphology. Optimization of oxygen‐plasma settings must therefore balance favorable effects such as contaminant removal, improved substrate wetting, and signal enhancement with deleterious effects such as structural damage to the substrate.
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- Award ID(s):
- 1655221
- PAR ID:
- 10453748
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Raman Spectroscopy
- Volume:
- 52
- Issue:
- 3
- ISSN:
- 0377-0486
- Format(s):
- Medium: X Size: p. 608-615
- Size(s):
- p. 608-615
- Sponsoring Org:
- National Science Foundation
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