| 1. |
- Löfstrand, Anette, et al.
(författare)
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Poly(styrene)- block-Maltoheptaose Films for Sub-10 nm Pattern Transfer : Implications for Transistor Fabrication
- 2021
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 4:5, s. 5141-5151
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Tidskriftsartikel (refereegranskat)abstract
- Sequential infiltration synthesis (SIS) into poly(styrene)-block-maltoheptaose (PS-b-MH) block copolymer using vapors of trimethyl aluminum and water was used to prepare nanostructured surface layers. Prior to the infiltration, the PS-b-MH had been self-assembled into 12 nm pattern periodicity. Scanning electron microscopy indicated that horizontal alumina-like cylinders of 4.9 nm diameter were formed after eight infiltration cycles, while vertical cylinders were 1.3 nm larger. Using homopolymer hydroxyl-terminated poly(styrene) (PS-OH) and MH films, specular neutron reflectometry revealed a preferential reaction of precursors in the MH compared to PS-OH. The infiltration depth into the maltoheptaose homopolymer film was found to be 2.0 nm after the first couple of cycles. It reached 2.5 nm after eight infiltration cycles, and the alumina incorporation within this infiltrated layer corresponded to 23 vol % Al2O3. The alumina-like material, resulting from PS-b-MH infiltration, was used as an etch mask to transfer the sub-10 nm pattern into the underlying silicon substrate, to an aspect ratio of approximately 2:1. These results demonstrate the potential of exploiting SIS into carbohydrate-based polymers for nanofabrication and high pattern density applications, such as transistor devices.
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| 2. |
- Löfstrand, Anette, et al.
(författare)
-
Sequential infiltration synthesis and pattern transfer using 6 nm half-pitch carbohydrate-based fingerprint block copolymer
- 2021
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Ingår i: Advances in Patterning Materials and Processes XXXVIII. - : SPIE. - 1996-756X .- 0277-786X. - 9781510640573 - 9781510640580 ; 11612
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Konferensbidrag (refereegranskat)abstract
- This study presents how sequential infiltration synthesis of trimethyl aluminium and water into a carbohydrate-based block copolymer was used to enable pattern transfer of 6 nm half-pitch horizontal cylinders into silicon. Specular neutron reflectometry measurements of poly(styrene)-block-maltoheptaose self-assembled into horizontal cylinders indicate an increasing content of alumina after each sequential infiltration cycle, comparing 0, 1, 2, and 4 cycles, with alumina content reaching 2.4 vol% after four infiltrations cycles. Dry etching processes in inductively coupled plasma reactive ion etching for sub-10 nm patterns were developed, using a two-step technique: O2-plasma for polymer removal and a reactive ion etching of Si using a mixture of SF6 and C4F8 gases. Etch selectivity of more than 2:1 of silicon over alumina-like etch mask material was achieved. To evaluate the etching process, the etched Si structures were measured and characterized by scanning electron microscopy. These results are expected to be of use for nanofabrication and applications in the sub-10 nm regime.
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| 3. |
- Mothander, Karolina
(författare)
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Grazing incidence small angle neutron scattering as a tool to study curved biomembranes on nanostructured surfaces
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Curvature in lipid-based biomembranes provides compartmentalization in cells and can act as regulator of biological activity in living systems. The study of these biomembranes require novel model systems and new methods. In this work I have used a supported phospholipid bilayer on a hexagonal array of silicon nanowires. The nanowires impose curvature on the supported lipid bilayer and the resulting structure has been investigated with a range of methods. Two main techniques have been used grazing incidence small angle neutron scattering (GISANS) and reflectometry. GISANS revealed the structure and coverage of the lipid bilayer on the nanowires, whereas reflectometry has been used to investigate the lipid bilayer on the flat areas between the nanowires. This makes the two techniques complementary, and the same bilayer has been studied on two different surfaces. In addition, confocal microscopy on fluorescently labeled lipids verified the formation of a lipid bilayer on the nanowire surface. Using fluorescence recovery after photobleaching (FRAP), I was able to verify that the formed lipid bilayer was continuous and mobile. To analyze the GISANS data a new method has been developed, which is based on the ratios of integrated peak intensities. These ratios were then compared with ratios of model-calculated form factors. This approach simplifies the analysis of the data, and allows for information on the lipid layer to be obtained directly.
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| 4. |
- Wilts, Bodo D., et al.
(författare)
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Humidity-dependent colour change in the green forester moth, Adscita statices
- 2019
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Ingår i: Biology letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 15:9
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Tidskriftsartikel (refereegranskat)abstract
- The colours of insects serve important visual functions in aiding mate recognition, camouflage and warning. The display of insects is usually static, as cuticle coloration does not (or hardly) change during the lifespan of a mature imago form. Here, we describe a case of humidity-dependent, brilliant coloration in the green forester moth, Adscita statices. We show, by employing spectroscopic and ultrastructural methods, that the moth's colour results from the interference of incident light with an unusual hydrophilic melanized-chitin multilayer present in the wing scales. Humidity changes in the environment affect the multilayer properties, causing a significant shift of the green-peaking reflectance in the dry state to a rusty colour when damp, resulting in the strong colour change between day and dusk or dawn.
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