@article{lemaire_parsons_2017, title={Thermal Selective Vapor Etching of TiO2: Chemical Vapor Etching via WF6 and Self-Limiting Atomic Layer Etching Using WF6 and BCl3}, volume={29}, ISSN={["1520-5002"]}, url={https://doi.org/10.1021/acs.chemmater.7b00985}, DOI={10.1021/acs.chemmater.7b00985}, abstractNote={Controlled thin film etching is essential for further development of sub-10 nm semiconductor devices. Vapor-phase thermal etching of oxides is appealing for achieving highly conformal etching of high aspect ratio features. We show that tungsten hexafluoride (WF6) can be used to selectively etch amorphous TiO2 films versus other oxides including Al2O3. Chemical vapor etching (CVE) of TiO2 by WF6 was studied with quartz crystal microbalance (QCM), spectroscopic ellipsometry, X-ray photoelectron spectroscopy (XPS), and thermodynamic modeling. The XPS results show evidence for a WOxFy layer that forms on of the TiO2 films during the etch process, which may act as a surfactant layer to help enable fluorination of the TiO2. Direct CVE of TiO2 by WF6 is strongly temperature dependent, where etching proceeds readily at 220 °C, but not at T ≤ 170 °C. This is consistent with thermodynamic modeling showing that the etching rate is determined by the volatilization of metal fluoride and WF2O2 product species. We also ...}, number={16}, journal={CHEMISTRY OF MATERIALS}, publisher={American Chemical Society (ACS)}, author={Lemaire, Paul C. and Parsons, Gregory N.}, year={2017}, month={Aug}, pages={6653–6665} }
 @article{lemaire_king_parsons_2017, title={Understanding inherent substrate selectivity during atomic layer deposition: Effect of surface preparation, hydroxyl density, and metal oxide composition on nucleation mechanisms during tungsten ALD}, volume={146}, ISSN={["1089-7690"]}, url={https://doi.org/10.1063/1.4967811}, DOI={10.1063/1.4967811}, abstractNote={Area-selective thin film deposition is expected to be important for advanced sub-10 nanometer semiconductor devices, enabling feature patterning, alignment to underlying structures, and edge definition. Several atomic layer deposition (ALD) processes show inherent propensity for substrate-dependent nucleation. This includes tungsten ALD (W-ALD) which is more energetically favorable on Si than on SiO2. However, the selectivity is often lost after several ALD cycles. We investigated the causes of tungsten nucleation on SiO2 and other “non-growth” surfaces during the WF6/SiH4 W-ALD process to determine how to expand the “selectivity window.” We propose that hydroxyls, generated during the piranha clean, act as nucleation sites for non-selective deposition and show that by excluding the piranha clean or heating the samples, following the piranha clean, extends the tungsten selectivity window. We also assessed how the W-ALD precursors interact with different oxide substrates though individual WF6 and SiH4 pre-exposures prior to W-ALD deposition. We conclude that repeated SiH4 pre-exposures reduce the tungsten nucleation delay, which is attributed to SiH4 adsorption on hydroxyl sites. In addition, oxide surfaces were repeatedly exposed to WF6, which appears to form metal fluoride species. We attribute the different tungsten nucleation delay on Al2O3 and TiO2 to the formation of nonvolatile and volatile metal fluoride species, respectively. Through this study, we have increased the understanding of ALD nucleation and substrate selectivity, which are pivotal to improving the selectivity window for W-ALD and other ALD processes.}, number={5}, journal={JOURNAL OF CHEMICAL PHYSICS}, publisher={AIP Publishing}, author={Lemaire, Paul C. and King, Mariah and Parsons, Gregory N.}, year={2017}, month={Feb} }
 @article{lemaire_zhao_williams_walls_shepherd_losego_peterson_parsons_2016, title={Copper Benzenetricarboxylate Metal-Organic Framework Nucleation Mechanisms on Metal Oxide Powders and Thin Films formed by Atomic Layer Deposition}, volume={8}, ISSN={["1944-8244"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000374274900078&KeyUID=WOS:000374274900078}, DOI={10.1021/acsami.6b01195}, abstractNote={Chemically functional microporous metal-organic framework (MOF) crystals are attractive for filtration and gas storage applications, and recent results show that they can be immobilized on high surface area substrates, such as fiber mats. However, fundamental knowledge is still lacking regarding initial key reaction steps in thin film MOF nucleation and growth. We find that thin inorganic nucleation layers formed by atomic layer deposition (ALD) can promote solvothermal growth of copper benzenetricarboxylate MOF (Cu-BTC) on various substrate surfaces. The nature of the ALD material affects the MOF nucleation time, crystal size and morphology, and the resulting MOF surface area per unit mass. To understand MOF nucleation mechanisms, we investigate detailed Cu-BTC MOF nucleation behavior on metal oxide powders and Al2O3, ZnO, and TiO2 layers formed by ALD on polypropylene substrates. Studying both combined and sequential MOF reactant exposure conditions, we find that during solvothermal synthesis ALD metal oxides can react with the MOF metal precursor to form double hydroxy salts that can further convert to Cu-BTC MOF. The acidic organic linker can also etch or react with the surface to form MOF from an oxide metal source, which can also function as a nucleation agent for Cu-BTC in the mixed solvothermal solution. We discuss the implications of these results for better controlled thin film MOF nucleation and growth.}, number={14}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Lemaire, Paul C. and Zhao, Junjie and Williams, Philip S. and Walls, Howard J. and Shepherd, Sarah D. and Losego, Mark D. and Peterson, Gregory W. and Parsons, Gregory N.}, year={2016}, month={Apr}, pages={9514–9522} }
 @article{lemaire_oldham_parsons_2016, title={Rapid visible color change and physical swelling during water exposure in triethanolamine-metalcone films formed by molecular layer deposition}, volume={34}, ISSN={["1520-8559"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000375115800035&KeyUID=WOS:000375115800035}, DOI={10.1116/1.4937222}, abstractNote={Molecular layer deposition (MLD) of “metalcones,” including alucone, zincone, titanicone, and others, involves self-limiting half-reactions between organic and organometallic (or metal-halide) reactants. Studies have typically focused on metal precursors reacting with ethylene glycol or glycerol to form the films' polymeric O-M-O-(CHx)y-O-M-O repeat units. The authors report new MLD materials that incorporate tertiary amine groups into the organic linkage. Specifically, reacting triethanolamine (TEA) with either trimethylaluminum or titanium tetrachloride produces TEA-alucone (Al-TEA) and TEA-titanicone (Ti-TEA), respectively, and the amine group leads to unique physical and optical properties. Fourier-transform infrared (FTIR) analysis confirms that the films have prominent C-H, C-N, and M-O-C peaks, consistent with the expected bond structure. When exposed to vapors, including water, alcohol, or ammonia, the Ti-TEA films changed their visible color within minutes and increased physical thickness by >35%. The Al-TEA showed significantly less response. X-ray photoelectron spectroscopy and FTIR suggest that HCl generated during MLD coordinates to the amine forming a quaternary ammonium salt that readily binds adsorbates via hydrogen bonding. The visible color change is reversible, and ellipsometry confirms that the color change results from vapor absorption. The unique absorptive and color-changing properties of the TEA-metalcone films point to new possible applications for MLD materials in filtration, chemical absorption, and multifunctional chemical separations/sensing device systems.}, number={1}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Lemaire, Paul C. and Oldham, Christopher J. and Parsons, Gregory N.}, year={2016}, month={Jan} }
 @article{kalanyan_lemaire_atanasov_ritz_parsons_2016, title={Using Hydrogen To Expand the Inherent Substrate Selectivity Window During Tungsten Atomic Layer Deposition}, volume={28}, ISSN={["1520-5002"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000368322600017&KeyUID=WOS:000368322600017}, DOI={10.1021/acs.chemmater.5b03319}, abstractNote={Area-selective thin film deposition is expected to be important in achieving sub-10 nm semiconductor devices, enabling feature patterning, alignment to underlying structures, and edge definition. Atomic layer deposition (ALD) offers advantages over common chemical vapor deposition methods, such as precise thickness control and excellent conformality. Furthermore, several ALD processes show inherent propensity for substrate-dependent nucleation. For example, tungsten ALD using SiH4 (or Si2H6) and WF6 is more energetically favorable on Si than on SiO2, but selectivity is often lost after several ALD cycles. We show that modifying the W ALD process chemistry can decrease the W nucleation rate on SiO2, thereby expanding the ALD “selectivity window”. Specifically, we find that adding H2 during the WF6 dose step helps passivate SiO2 against W nucleation without modifying W growth on silicon. Surface characterization confirms that H2 promotes fluorine passivation of SiO2, likely through surface reactions with HF...}, number={1}, journal={CHEMISTRY OF MATERIALS}, author={Kalanyan, Berc and Lemaire, Paul C. and Atanasov, Sarah E. and Ritz, Mariah J. and Parsons, Gregory N.}, year={2016}, month={Jan}, pages={117–126} }
 @article{dandley_lemaire_zhu_yoon_sheet_parsons_2016, title={Wafer-Scale Selective-Area Deposition of Nanoscale Metal Oxide Features Using Vapor Saturation into Patterned Poly(methyl methacrylate) Templates}, volume={3}, ISSN={["2196-7350"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000370043000006&KeyUID=WOS:000370043000006}, DOI={10.1002/admi.201500431}, abstractNote={Patterned, chemically reactive poly(methyl)methacrylate can act as a chemical “sponge” via Lewis acid/base adduct formation with metal‐organic reactants commonly used in atomic layer deposition. Extended reactant exposures saturate the reactant within the polymer, and subsequent oxidation removes the polymer and converts the saturated reactant to a metal oxide film that precisely mimics the lateral dimensions of the original polymer. Resulting oxide thickness scales with the starting polymer thickness. Regions without polymer are coated with less than 1 nm of metal oxide. Repeatable nanoscale features are formed simultaneously and uniformly across a 150 mm diameter silicon wafer.}, number={2}, journal={ADVANCED MATERIALS INTERFACES}, author={Dandley, Erinn C. and Lemaire, Paul C. and Zhu, Zhongwei and Yoon, Alex and Sheet, Lubab and Parsons, Gregory N.}, year={2016}, month={Jan} }
 @article{zhao_gong_nunn_lemaire_stevens_sidi_williams_oldham_walls_shepherd_et al._2015, title={Conformal and highly adsorptive metal-organic framework thin films via layer-by-layer growth on ALD-coated fiber mats}, volume={3}, ISSN={["2050-7496"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000346906100014&KeyUID=WOS:000346906100014}, DOI={10.1039/c4ta05501b}, abstractNote={Fiber@ALD@MOF structures fabricated via ALD and layer-by-layer MOF synthesis show good conformality and high adsorption capacity.}, number={4}, journal={JOURNAL OF MATERIALS CHEMISTRY A}, author={Zhao, Junjie and Gong, Bo and Nunn, William T. and Lemaire, Paul C. and Stevens, Eric C. and Sidi, Fahim I. and Williams, Philip S. and Oldham, Christopher J. and Walls, Howard J. and Shepherd, Sarah D. and et al.}, year={2015}, pages={1458–1464} }
 @article{zhao_nunn_lemaire_lin_dickey_oldham_walls_peterson_losego_parsons_et al._2015, title={Facile Conversion of Hydroxy Double Salts to Metal-Organic Frameworks Using Metal Oxide Particles and Atomic Layer Deposition Thin-Film Templates}, volume={137}, ISSN={["1520-5126"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000364355900009&KeyUID=WOS:000364355900009}, DOI={10.1021/jacs.5b08752}, abstractNote={Rapid room-temperature synthesis of metal-organic frameworks (MOFs) is highly desired for industrial implementation and commercialization. Here we find that a (Zn,Cu) hydroxy double salt (HDS) intermediate formed in situ from ZnO particles or thin films enables rapid growth (<1 min) of HKUST-1 (Cu3(BTC)2) at room temperature. The space-time-yield reaches >3 × 10(4) kg·m(-3)·d(-1), at least 1 order of magnitude greater than any prior report. The high anion exchange rate of (Zn,Cu) hydroxy nitrate HDS drives the ultrafast MOF formation. Similarly, we obtained Cu-BDC, ZIF-8, and IRMOF-3 structures from HDSs, demonstrating synthetic generality. Using ZnO thin films deposited via atomic layer deposition, MOF patterns are obtained on pre-patterned surfaces, and dense HKUST-1 coatings are grown onto various form factors, including polymer spheres, silicon wafers, and fibers. Breakthrough tests show that the MOF-functionalized fibers have high adsorption capacity for toxic gases. This rapid synthesis route is also promising for new MOF-based composite materials and applications.}, number={43}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, publisher={American Chemical Society (ACS)}, author={Zhao, Junjie and Nunn, William T. and Lemaire, Paul C. and Lin, Yiliang and Dickey, Michael and Oldham, Christopher J. and Walls, Howard J. and Peterson, Gregory W. and Losego, Mark D. and Parsons, Gregory N. and et al.}, year={2015}, month={Nov}, pages={13756–13759} }
 @article{kim_atanasov_lemaire_lee_parsons_2015, title={Platinum-Free Cathode for Dye-Sensitized Solar Cells Using Poly(3,4-ethylenedioxythiophene) (PEDOT) Formed via Oxidative Molecular Layer Deposition}, volume={7}, ISSN={["1944-8244"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000350193000002&KeyUID=WOS:000350193000002}, DOI={10.1021/am5084418}, abstractNote={Thin ∼ 20 nm conformal poly(3,4-ehylenedioxythiophene) (PEDOT) films are incorporated in highly conductive mesoporous indium tin oxide (m-ITO) by oxidative molecular layer deposition (oMLD). These three-dimensional catalytic/conductive networks are successfully employed as Pt-free cathodes for dye-sensitized solar cells (DSSCs) with open circuit voltage equivalent to Pt cathode devices. Thin and conformal PEDOT films on m-ITO by oMLD create high surface area and efficient electron transport paths to promote productive reduction reaction on the PEDOT film. Because of these two synergetic effects, PEDOT-coated m-ITO by oMLD shows power conversion efficiency, 7.18%, comparable to 7.26% of Pt, and higher than that of planar PEDOT coatings, which is 4.85%. Thus, PEDOT-coated m-ITO is an exceptional opportunity to compete with Pt catalysts for low-cost energy conversion devices.}, number={7}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Kim, Do Han and Atanasov, Sarah E. and Lemaire, Paul and Lee, Kyoungmi and Parsons, Gregory N.}, year={2015}, month={Feb}, pages={3866–3870} }
 @article{zhao_losego_lemaire_williams_gong_atanasov_blevins_oldham_walls_shepherd_et al._2014, title={Highly adsorptive, MOF-functionalized nonwoven fiber mats for hazardous gas capture enabled by atomic layer deposition}, volume={1}, number={4}, journal={Advanced Materials Interfaces}, author={Zhao, J. J. and Losego, M. D. and Lemaire, P. C. and Williams, P. S. and Gong, B. and Atanasov, S. E. and Blevins, T. M. and Oldham, C. J. and Walls, H. J. and Shepherd, S. D. and et al.}, year={2014} }