This is the first report on a plasma enhanced spatial atomic layer deposition (APP-ALD) process at atmospheric pressure to grow conducting metallic Cu thin films from a carbene stabilized precursor.
Owing to the limited availability of suitable precursors for vaporp hase deposition of rare-earth containing thin-filmm aterials, new or improved precursors are sought after.I nt his study,w ee xplored new precursors for atomic layer deposition(ALD)o fc erium (Ce) and ytterbium(Yb) containing thin films. As eries of homoleptic tris-guanidinate and tris-amidinatec omplexes of cerium (Ce) and ytterbium (Yb) were synthesized andt horoughlyc haracterized. The Csubstituents on the N-C-N backbone (Me, NMe 2 ,N Et 2 ,w here Me = methyl, Et = ethyl) and the N-substituents from symmetrical iso-propyl (iPr) to asymmetrical tertiary-butyl (tBu) and Et were systematically varied to study the influence of the substituents on the physicochemical properties of the resulting compounds. Single crystal structures of [Ce(dpdmg) 3 ] 1 and [Yb(dpdmg) 3 ] 6 (dpdmg = N,N'-diisopropyl-2-dimethylamido-guanidinate) highlightamonomeric nature in the solid-state with ad istorted trigonal prismatic geometry.T he thermogravimetric analysis shows that the complexes are volatile and emphasize that increasing asym-metryi nt he complexes lowers their meltingp oints while reducingt heir thermal stability.D ensityf unctionalt heory (DFT) was used to study the reactivity of amidinates and guanidinates of Ce and Yb complexes towards oxygen (O 2) and water (H 2 O). Signified by the DFT calculations, the guanidinates show an increased reactivity toward water compared to the amidinate complexes. Furthermore,t he Ce complexes are more reactive compared to the Yb complexes,i ndicating even ar eactivity towards oxygen potentiallye xploitable for ALD purposes. As arepresentative precursor,the highly reactive [Ce(dpdmg) 3 ] 1 wasu sed for proof-of-principleA LD depositions of CeO 2 thin films using watera sc o-reactant. The self-limited ALD growth process could be confirmed at 160 8Cw ithp olycrystalline cubic CeO 2 films formed on Si(100) substrates. This study confirmst hat moving towards nitrogen-coordinated rare-earth complexes bearing the guanidinate and amidinate ligands can indeed be very appealing in terms of new precursors for ALD of rare earth based materials.
The synthesis and characterization of a series of closely related Y(III) compounds comprising the formamidinate ligands (RNCHNR) (R = alkyl) is reported, with the scope of using them as prospective...
First principles investigation of the molecular mechanism of Al2O3-based hybrid materials grown with homo- or hetero-bifunctional aromatic compounds with hydroxy (OH) and/or amino (NH2) terminal groups.
First principles investigation of the molecular mechanism of the growth of hybrid organic–inorganic thin films of aluminium alkoxides, known as “alucones”.
Nanoscale patterning of inorganics is crucial for the
fabrication
of advanced electronic, photonic, and energy devices. The emerging
sequential infiltration synthesis (SIS) method fabricates nanofeatures
by block-selective vapor-phase growth in block copolymer templates
with tunable patterns. Yet, SIS has been demonstrated mainly for Al2O3 and a few other metal oxides, while deriving
metal nanostructures from a single SIS process is a challenge. Here,
we present SIS of the Ru metal in polystyrene-block-polymethyl methacrylate
(PS-b-PMMA) templates without any pretreatment, using alternating
infiltration of RuO4 and H2. RuO4 interacts selectively and strongly with the aromatic CC
and C–H groups in PS, leaving the PMMA domains inert. Density
functional theory calculations corroborate that the PS–RuO4 interaction is energetically favorable, with a calculated
interaction energy of −1.65 eV, whereas for PMMA–RuO4, the calculated energy of −0.05 eV indicates an unfavorable
interaction. Morphological analysis on the di-BCP after the RuO4-H2 process indicates an increase in contrast as
a function of SIS cycles and templated Ru incorporation. The crystalline
nature of the Ru deposits is confirmed using grazing incidence wide-angle
X-ray scattering. Plasma-aided removal of the organic components yields
Ru nanolines with lateral dimensions of ca 20 nm. We further highlight
the broad potential of RuO4 as a reactant for SIS by generating
RuO2 nanopatterns via alternating RuO4 and methanol
infiltration.
Organic-inorganic hybrid materials are a unique class of materials with properties driven by the organic and inorganic components, making them useful for flexible devices. Molecular layer deposition (MLD) offers novel pathways for the fabrication of such hybrids by using inorganic metal precursors and the vast range of organic molecules with tunable properties. To investigate and understand the mechanism of growth a combination of theoretical and experimental data is needed. In this contribution, we present a first principles investigation of the molecular mechanism of the growth of hybrid organic−inorganic thin films of aluminium alkoxides, known as "alucones" grown by MLD. We explore the interactions between precursors by analyzing the MLD reaction products of the alumina surface terminated with Al(CH3) groups after the trimethyl aluminium pulse; this yields monomethyl-Al2O3 (Al-CH3-Al2O3) and dimethyl-Al2O3 (Al(CH3)2-Al2O3) terminated surfaces. The organic precursors are ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TEG) and tetraethylene glycol (FEG). A detailed comparison with alucones grown with ethylene glycol (EG) and glycerol (GL) precursors is presented to assist the interpretation of experimental findings regarding the differences in the hybrid films grown by EG and GL. The results show that Al-O formation with release of methane is favorable for all precursors. EG and GL can lie flat and create so-called double reactions through the reaction of the two terminal hydroxyl groups with the surface fragments. This phenomenon removes active hydroxyl sites for EG. However, for GL the third hydroxyl group is available and growth can proceed. This analysis shows the origin of differences in thickness of alucones found for EG and GL.
Atomic / molecular layer deposition (ALD/MLD) process for the fabrication of cerium-based metal-organic hybrid films is demonstrated for the first time. The highly reactive cerium (III) guanidinate precursor [Ce(dpdmg)3] was...
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