Selective-Area Atomic Layer Deposition

Atomic layer deposition (ALD) is a method to deposit thin films from gaseous precursors to the substrate layer-by-layer so that the film thickness can be tailored with atomic layer accuracy. Film tailoring is even further emphasized with selective-area ALD which enables the film growth to be controlled also on the substrate surface. Selective-area ALD allows the decrease of a process steps in preparing thin film devices. This can be of a great technological importance when the ALD films become into wider use in different applications. Selective-area ALD can be achieved by passivation or activation of a surface. In this work ALD growth was prevented by octadecyltrimethoxysilane, octadecyltrichlorosilane and 1-dodecanethiol SAMs, and by PMMA (polymethyl methacrylate) and PVP (poly(vinyl pyrrolidone) polymer films. SAMs were prepared from vapor phase and by microcontact printing, and polymer films were spin coated. Microcontact printing created patterned SAMs at once. The SAMs prepared from vapor phase and the polymer mask layers were patterned by UV lithography or lift-off process so that after preparation of a continuous mask layer selected areas of them were removed. On these areas the ALD film was deposited selectively. SAMs and polymer films prevented the growth in several ALD processes such as iridium, ruthenium, platinum, TiO2 and polyimide so that the ALD films did grow only on areas without SAM or polymer mask layer. PMMA and PVP films also protected the surface against Al2O3 and ZrO2 growth. Activation of the surface for ALD of ruthenium was achieved by preparing a RuOX layer by microcontact printing. At low temperatures the RuCp2-O2 process nucleated only on this oxidative activation layer but not on bare silicon.Atomikerroskasvutus (atomic layer deposition, ALD) on menetelmä, jolla kasvatetaan ohutkalvoja kaasumaisista lähtöaineista kiinteälle pinnalle atomikerros kerrallaan, jolloin kalvon paksuus voidaan määritellä atomikerroksen tarkkuudella. Selektiivisellä ALD:llä kalvon kasvua voidaan kontrolloida myös pinnan suuntaisesti, jolloin kalvo voidaan kasvattaa ainoastaan halutuille alueille. Tämä vähentää välivaiheita ohutkalvolaitteiden valmistuksessa ja tulevaisuudessa selektiivisellä ALD:llä voi olla suuri merkitys kun ALD-kalvot tulevat laajempaan käyttöön erilaisissa sovelluksissa. Tässä työssä on kasvatettu selektiivisesti useita metalleja, metallioksideita ja polyimidiä passivoimalla pinta halutuilta alueilta. Passivointiin käytettiin joko SAM:eja (self-assembled monolayer, itsejärjestäytyvä monokerros) tai polymeerikalvoja. Kaasufaasista pii-pinnalle valmistettu oktadekyylitrimetoksisilaani-SAM ja kuparipinnalle valmistettu 1-dodekaanitioli-SAM estivät iridiumin kasvun ja tioli-SAM esti myös polyimidin kasvun. Mikrokontaktipainamisella valmistettu oktadekyylitrikloorisilaani-SAM esti sekä iridiumin että TiO2:n kasvun. Myös PMMA- (polymetyylimetakrylaatti) ja PVP- (polyvinyylipyrrolidoni) kalvoja käytettiin joko passivoimaan pinta ALD-kasvua vastaan tai suojaamaan pinta niin ettei kalvo kasvanut polymeerikalvon alla olevalle pinnalle. PMMA ja PVP estivät iridiumin, ruteenin ja platinan kasvun. PMMA esti lisäksi TiO2:n kasvun. Molemmat polymeerit suojasivat pinnan Al2O3- ja ZrO2-kasvulta. Kaikissa ALD-prosesseissa kalvo kasvoi alueille, joista SAM tai polymeerikalvo oli poistettu. Uusi lähestymistapa selektiiviseen ALD:hen on pinnan aktivointi, jolloin kalvo kasvatetaan ainoastaan alueille, joille ALD kasvu on tehty mahdolliseksi. Tässä työssä pii-pintaan valmistettiin RuOX-kalvo mikrokontaktipainamisella. Alhaisessa lämpötilassa ruteeni (RuCp2:sta ja O2:sta) kasvoi ainoastaan aktivoiduille alueille ja aktivoimattomat pii-alueet jäivät ilman ruteenia

As2S3 thin films deposited by atomic layer deposition

As2S3 thin films were deposited on glass and silicon (100) substrates by atomic layer deposition from tris(dimethylamino) arsine [(CH3)(2)N)(3)As] and H2S. Amorphous films were deposited at an exceptionally low temperature of 50 degrees C. No film growth was observed at higher temperatures. The films were amorphous and contained H and C as the main impurities. The refractive index was 2.3 at 1.0 mu m. The films were sensitive to air humidity, but their stability was significantly improved by a protective Al2O3 layer. (C) 2016 American Vacuum Society.Peer reviewe

Controlling the refractive index and third-order nonlinearity of polyimide/Ta2O5 nanolaminates for optical applications

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Photocatalytic and Gas Sensitive Multiwalled Carbon Nanotube/TiO2-ZnO and ZnO-TiO2 Composites Prepared by Atomic Layer Deposition

TiO2 and ZnO single and multilayers were deposited on hydroxyl functionalized multi-walled carbon nanotubes using atomic layer deposition. The bare carbon nanotubes and the resulting heterostructures were characterized by TG/DTA, Raman, XRD, SEM-EDX, XPS, TEM-EELS-SAED and low temperature nitrogen adsorption techniques, and their photocatalytic and gas sensing activities were also studied. The carbon nanotubes (CNTs) were uniformly covered with anatase TiO2 and wurtzite ZnO layers and with their combinations. In the photocatalytic degradation of methyl orange, the most beneficial structures are those where ZnO is the external layer, both in the case of single and double oxide layer covered CNTs (CNT-ZnO and CNT-TiO2-ZnO). The samples with multilayer oxides (CNT-ZnO-TiO2 and CNT-TiO2-ZnO) have lower catalytic activity due to their larger average densities, and consequently lower surface areas, compared to single oxide layer coated CNTs (CNT-ZnO and CNT-TiO2). In contrast, in gas sensing it is advantageous to have TiO2 as the outer layer. Since ZnO has higher conductivity, its gas sensing signals are lower when reacting with NH3 gas. The double oxide layer samples have higher resistivity, and hence a larger gas sensing response than their single oxide layer counterparts

Programming nanostructured soft biological surfaces by atomic layer deposition

Here, we present the first successful attempt to programme the surface properties of nanostructured soft biological tissues by atomic layer deposition (ALD). The nanopatterned surface of lotus leaf was tuned by 3-125 nm TiO2 thin films. The lotus/TiO2 composites were studied by SEM-EDX, XPS, Raman, TG-DTA, XRR, water contact angle and photocatalysis measurements. While we could preserve the superhydrophobic feature of lotus, we managed to add a new property, i.e. photocatalytic activity. We also explored how surface passivation treatments and various ALD precursors affect the stability of the sensitive soft biological tissues. As we were able to gradually change the number of nanopatterns of lotus, we gained new insight into how the hollow organic nanotubes on the surface of lotus influence its superhydrophobic feature

X-ray ptychographic computed tomography at 16 nm isotropic 3D resolution

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Photocatalytic and Gas Sensitive Multiwalled Carbon Nanotube/TiO2-ZnO and ZnO-TiO2 Composites Prepared by Atomic Layer Deposition

TiO2 and ZnO single and multilayers were deposited on hydroxyl functionalized multi-walled carbon nanotubes using atomic layer deposition. The bare carbon nanotubes and the resulting heterostructures were characterized by TG/DTA, Raman, XRD, SEM-EDX, XPS, TEM-EELS-SAED and low temperature nitrogen adsorption techniques, and their photocatalytic and gas sensing activities were also studied. The carbon nanotubes (CNTs) were uniformly covered with anatase TiO2 and wurtzite ZnO layers and with their combinations. In the photocatalytic degradation of methyl orange, the most beneficial structures are those where ZnO is the external layer, both in the case of single and double oxide layer covered CNTs (CNT-ZnO and CNT-TiO2-ZnO). The samples with multilayer oxides (CNT-ZnO-TiO2 and CNT-TiO2-ZnO) have lower catalytic activity due to their larger average densities, and consequently lower surface areas, compared to single oxide layer coated CNTs (CNT-ZnO and CNT-TiO2). In contrast, in gas sensing it is advantageous to have TiO2 as the outer layer. Since ZnO has higher conductivity, its gas sensing signals are lower when reacting with NH3 gas. The double oxide layer samples have higher resistivity, and hence a larger gas sensing response than their single oxide layer counterparts

Nanofocusing of hard X-ray free electron laser pulses using diamond based Fresnel zone plates

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