| 1. |
- Qi, B., et al.
(författare)
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A micro-spectroscopy study on the influence of chemical residues from nanofabrication on the nitridation chemistry of Al nanopatterns
- 2012
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 258:10, s. 4497-4506
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Tidskriftsartikel (refereegranskat)abstract
- We applied spatially resolved photoelectron spectroscopy implemented with an X-ray photoemission electron microscopy (XPEEM) using soft X-ray synchrotron radiation to identify the compositional and morphological inhomogeneities of a SiO2/Si substrate surface nanopatterned with Al before and after nitridation. The nanofabrication was conducted by a polymethylmethacrylate (PMMA)-based e-beam lithography and a fluorine-based reactive ion etching (RIE), followed by Al metalization and acetone lift-off. Three types of chemical residues were identified before nitridation: (1) fluorocarbons produced and accumulated mainly during RIE process on the sidewalls of the nanopatterns; (2) a thick Al-bearing PMMA layer and/or (3) a thin PMMA residue layer owing to unsuccessful or partial lift-off of the e-beam unexposed PMMA between the nanopatterns. The fluorocarbons actively influenced the surface chemical composition of the nanopatterns by forming Al-F compounds. After nitridation, in the PMMA residue-free area, the Al-F compounds on the sidewalls were decomposed and transformed to AIN. The PMMA residues between the nanopatterns had no obvious influence on the surface chemical composition and nitridation properties of the Al nanopatterns. They were only partially decomposed by the nitridation. The regional surface morphology of the nanopatterns revealed by the secondary electron XPEEM was consistent with the scanning electron microscopy results.
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| 2. |
- Qi, B., et al.
(författare)
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Formation and nitridation of InGa composite droplets on Si(111) : In-situ study by high resolution X-ray photoelectron spectroscopy
- 2014
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 303, s. 297-305
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate applying synchrotron radiation based high resolution X-ray photoelectron spectroscopy as a versatile in-situ tool to study the step-wise formation and nitridation of indium gallium (InGa) composite droplets on Si(1 1 1) 7 x 7. This includes analysis of initial interactions of Ga and In with Si(1 1 1)7x7, and characterization of formation and nitridation of InGa droplets. The results show that after stabilization of Si(1 1 1) 7 x 7 structure with Ga and In at 750 degrees C and formation of Ga nanodroplets as the bases, the InGa composite droplets (In:Ga approximate to 3:1) were formed at RT and 200 degrees C in a coverage range 3-14 monolayers. The nitridation efficiency and structure of the droplets/Si(1 1 1) with NH3 were temperature dependent. At or below 350 degrees C, the droplets were hardly nitridated. At 670 degrees C, the nitridation of InGa was more completed, which however caused an unavoidable nitridation of Si surface. The optimum nitridation occurred around 480 degrees C and proceed in a 2D mode. Further simultaneous growth and nitridation of the InGa droplets on the 2D nitridated surface at 400 degrees C resulted in a complex surface composition and structure. An ex-situ atomic force microscopy reveals both the aligned metallic droplet-island assemblies and the fractured nitridated island bases with small droplets on top for the final surface.
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| 3. |
- Qi, B., et al.
(författare)
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Study of spatial homogeneity and nitridation of an Al nanopattern template with spectroscopic photoemission and low energy electron microscopy
- 2013
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 264, s. 349-357
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Tidskriftsartikel (refereegranskat)abstract
- We report a study on the spatial homogeneity and nitridation of a nanopattern template using a spectroscopic photoemission and low energy electron microscopy. The template was composed of Al nanodots which were patterned into a SiO2/Si(1 1 1) surface using e-beam lithography and reactive ion etching. The template exhibited a global inhomogeneity in terms of the local topography, Al composition and structure of the individual nanopatterns. After nitridation, the individual nanopatterns were diminished, more corrugated and faceted. The nitridated nanopatterns were structurally ordered but differently orientated. The nitridation effectively removed the fluorine contaminants by decomposition of the fluorocarbon sidewalls, resulting in the AlN nanopatterns and partially nitridated Si substrate surface outside the nanopattern domains.
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