@article{carroll_margavio_parsons_2024, title={"Dual-Tone" Area-Selective Deposition: Selectivity Inversion of Polymer on Patterned Si/SiO<sub>2</sub> Starting Surfaces}, volume={2}, ISSN={["1520-5002"]}, url={https://doi.org/10.1021/acs.chemmater.3c03158}, DOI={10.1021/acs.chemmater.3c03158}, abstractNote={Area-selective deposition (ASD) has recently emerged as a promising augmentation of lithographic patterning of small device features. However, current ASD processes are restricted to predefined growth and nongrowth surfaces, limiting their flexibility in industrial processing. In this work, we define the concept of "dual-tone ASD," where a patterned surface is tuned to enable ASD on one of two adjacent surfaces while avoiding growth on the other surface. For the example case in this work, starting with ASD of the poly(3,4-ethylenedioxythipohene) (PEDOT) conjugated polymer on SiO2 vs on hydrogen-terminated silicon (Si–H), we demonstrate a method to modify a patterned Si–H/SiO2 surface to invert the selectivity, enabling PEDOT to grow selectively on the modified Si region and not on the modified SiO2. The selectivity inversion was achieved by selective modification of the substrate surface energy via treatments with dilute hydrofluoric acid (DHF), (dimethylamino)trimethylsilane (DMATMS), and water. Versatile control over selectivity configurations during ASD has implications for deposition of lateral control layers to reduce overgrowth defects, blocking layers for nonselective deposition steps, and sacrificial layers for recently reported simultaneous deposition and etching processes. Through this study, we identify generalized requirements for selectivity inversion as a patterning strategy in the ASD toolbox and show how this strategy is consistent with previous reports of ASD on metal–dielectric patterned surfaces. Extension of these surface energy treatment strategies to other materials will provide additional opportunities for selectivity inversion, leading to flexible applications of ASD in manufacturing settings.}, journal={CHEMISTRY OF MATERIALS}, author={Carroll, Nicholas M. and Margavio, Hannah R. M. and Parsons, Gregory N.}, year={2024}, month={Feb} }
 @article{oyetade_wang_he_margavio_bottum_rooney_wang_donley_parsons_cohen-karni_et al._2024, title={Covalent Functionalization of Silicon with Plasma-Grown "Fuzzy" Graphene: Robust Aqueous Photoelectrodes for CO<sub>2</sub> Reduction by Molecular Catalysts}, volume={7}, ISSN={["1944-8252"]}, url={https://doi.org/10.1021/acsami.4c04691}, DOI={10.1021/acsami.4c04691}, abstractNote={Carbon electrodes are ideal for electrochemistry with molecular catalysts, exhibiting facile charge transfer and good stability. Yet for solar-driven catalysis with semiconductor light absorbers, stable semiconductor/carbon interfaces can be difficult to achieve, and carbon's high optical extinction means it can only be used in ultrathin layers. Here, we demonstrate a plasma-enhanced chemical vapor deposition process that achieves well-controlled deposition of out-of-plane "fuzzy" graphene (FG) on thermally oxidized Si substrates. The resulting Si|FG interfaces possess a silicon oxycarbide (SiOC) interfacial layer, implying covalent bonding between Si and the FG film that is consistent with the mechanical robustness observed from the films. The FG layer is uniform and tunable in thickness and optical transparency by deposition time. Using}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Oyetade, Oluwaseun A. and Wang, Yingqiao and He, Shi and Margavio, Hannah R. M. and Bottum, Samuel R. and Rooney, Conor L. and Wang, Hailiang and Donley, Carrie L. and Parsons, Gregory N. and Cohen-Karni, Tzahi and et al.}, year={2024}, month={Jul} }
 @article{oh_thelven_margavio_parsons_2024, title={Low-Temperature Dual-Material Area-Selective Deposition: Molybdenum Hexafluoride-Mediated SiO<sub>2</sub> Fluorination/Passivation for Self-Aligned Molybdenum/Metal Oxide Nanoribbons}, volume={4}, ISSN={["1616-3028"]}, url={https://doi.org/10.1002/adfm.202316872}, DOI={10.1002/adfm.202316872}, abstractNote={Abstract Area‐selective deposition (ASD) is a forefront nanopatterning technique gaining substantial attention in the semiconductor industry. While current research primarily addresses single‐material ASD, exploring multi‐material ASD is essential for mitigating complexity in advanced nanopatterning. This study describes molybdenum hexafluoride (MoF 6 )‐mediated fluorination/passivation of the hydroxylated SiO 2 (SiO 2 ‒OH) at 250 °C as a new method to pacify nucleation during subsequent ZnO and TiO 2 atomic layer deposition (ALD). In contrast, Al 2 O 3 ALD is not passivated on the fluorinated SiO 2 (SiO 2 ‒F). The study further shows that Mo ALD using MoF 6 and silane (1 wt% SiH 4 in Ar) selectively proceeds on hydrogen‐terminated Si (Si‒H), whereas SiO 2 ‒OH becomes fluorine‐passivated without observable Mo deposition. This enables subsequent ZnO and TiO 2 ASD on Mo versus SiO 2 ‒F, as confirmed by X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and scanning transmission electron microscopy (STEM). Proposed growth and inhibition mechanisms highlight the importance of the metal oxide precursor in achieving selectivity. Taken together, self‐aligned Mo/ZnO and Mo/TiO 2 nanoribbons are demonstrated on coplanar nanoscale Si‒H/SiO 2 ‒OH patterns by sequentially integrating two individual ASD processes: 1) Mo ASD on Si‒H versus SiO 2 ‒OH; and 2) ZnO or TiO 2 ASD on Mo versus SiO 2 ‒F. This work highlights the potential for this approach in new ASD systems.}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Oh, Hwan and Thelven, Jeremy M. and Margavio, Hannah R. M. and Parsons, Gregory N.}, year={2024}, month={Apr} }
 @article{nedzbala_westbroek_margavio_yang_noh_magpantay_donley_kumbhar_parsons_mayer_2024, title={Photoelectrochemical Proton-Coupled Electron Transfer of TiO<sub>2</sub> Thin Films on Silicon}, volume={4}, ISSN={["1520-5126"]}, url={https://doi.org/10.1021/jacs.4c00014}, DOI={10.1021/jacs.4c00014}, abstractNote={TiO2 thin films are often used as protective layers on semiconductors for applications in photovoltaics, molecule–semiconductor hybrid photoelectrodes, and more. Experiments reported here show that TiO2 thin films on silicon are electrochemically and photoelectrochemically reduced in buffered acetonitrile at potentials relevant to photoelectrocatalysis of CO2 reduction, N2 reduction, and H2 evolution. On both n-type Si and irradiated p-type Si, TiO2 reduction is proton-coupled with a 1e–:1H+ stoichiometry, as demonstrated by the Nernstian dependence of the Ti4+/3+ E1/2 on the buffer pKa. Experiments were conducted with and without illumination, and a photovoltage of ∼0.6 V was observed across 20 orders of magnitude in proton activity. The 4 nm films are almost stoichiometrically reduced under mild conditions. The reduced films catalytically transfer protons and electrons to hydrogen atom acceptors, based on cyclic voltammogram, bulk electrolysis, and other mechanistic evidence. TiO2/Si thus has the potential to photoelectrochemically generate high-energy H atom carriers. Characterization of the TiO2 films after reduction reveals restructuring with the formation of islands, rendering TiO2 films as a potentially poor choice as protecting films or catalyst supports under reducing and protic conditions. Overall, this work demonstrates that atomic layer deposition TiO2 films on silicon photoelectrodes undergo both chemical and morphological changes upon application of potentials only modestly negative of RHE in these media. While the results should serve as a cautionary tale for researchers aiming to immobilize molecular monolayers on "protective" metal oxides, the robust proton-coupled electron transfer reactivity of the films introduces opportunities for the photoelectrochemical generation of reactive charge-carrying mediators.}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Nedzbala, Hannah S. and Westbroek, Dalaney and Margavio, Hannah R. M. and Yang, Hyuenwoo and Noh, Hyunho and Magpantay, Samantha V. and Donley, Carrie L. and Kumbhar, Amar S. and Parsons, Gregory N. and Mayer, James M.}, year={2024}, month={Apr} }
 @article{zhirnov_chen_malakoutian_margavio_pawliczak_reidy_yanez_younkin_2023, title={SRC-led materials research: 40 years ago, and now}, ISSN={["2059-8521"]}, DOI={10.1557/s43580-023-00665-4}, abstractNote={Today, we are living through a pivotal moment when the semiconductor industry is moving towards 3D-integration including the close integration of logic and memory, the tighter integration of mixed-signal circuits, spintronic, embedded memories, sensors, communications, and improved power management. It is expected that 3D monolithic and heterogeneous integration will result in a new, truly multi-functional platform that drives continued system progress in the coming decades. Thus, over the next 40 years, the semiconductor industry will require significant innovation. At the heart of that is the need for significant contributions from the materials ecosystem to drive materials from the laboratory to the factory. For this perspective article, a selected group of distinguished SRC Scholars have been invited to present their research in the context of the potential impact that their work will drive for the future of microelectronics.}, journal={MRS ADVANCES}, author={Zhirnov, Victor and Chen, Michelle E. and Malakoutian, Mohamadali and Margavio, Hannah R. M. and Pawliczak, Emma and Reidy, Kate and Yanez, Wilson and Younkin, Todd}, year={2023}, month={Nov} }
 @article{oh_kim_margavio_parsons_2023, title={Self-Aligned Nanopatterning and Controlled Lateral Growth by Dual-Material Orthogonal Area-Selective Deposition of Poly(3,4-ethylenedioxythiophene) and Tungsten}, volume={35}, ISSN={["1520-5002"]}, url={https://doi.org/10.1021/acs.chemmater.3c00530}, DOI={10.1021/acs.chemmater.3c00530}, abstractNote={Despite recent advances in area-selective deposition (ASD) processes, most studies have focused on single-material ASD. Multi-material ASD processes could provide additional flexibility for fabricating semiconductor devices. In this work, we identify process requirements to sequentially combine two intrinsic ASD processes: (1) poly(3,4-ethylenedioxythiophene) (PEDOT) ASD on SiO2 vs Si–H via oxidative chemical vapor deposition and (2) W ASD on Si–H vs SiO2 via atomic layer deposition. Using ex situ X-ray photoelectron spectroscopy, we show that a preferred orthogonal ASD sequence involves PEDOT ASD on SiO2 vs Si–H, followed by W ASD on Si–H vs PEDOT. We find that the properties of the individual PEDOT and W ASD materials, including resistivity, surface roughness, and growth rate, are affected by the ASD sequence. Furthermore, we successfully demonstrate that orthogonal ASD can be extended to nanoscale starting patterns. The cross-sectional scanning transmission electron microscopy (STEM) with energy-dispersive X-ray spectroscopy analysis shows that the resulting PEDOT thickness on SiO2 depends on feature geometry and dimension. Finally, we demonstrate the feasibility that the PEDOT layer can control the lateral growth of W onto the non-growth surface.}, number={11}, journal={CHEMISTRY OF MATERIALS}, author={Oh, Hwan and Kim, Jung-Sik and Margavio, Hannah R. M. and Parsons, Gregory N.}, year={2023}, month={May}, pages={4375–4384} }
 @article{song_kim_margavio_parsons_2021, title={Multimaterial Self-Aligned Nanopatterning by Simultaneous Adjacent Thin Film Deposition and Etching}, volume={15}, ISSN={["1936-086X"]}, url={https://doi.org/10.1021/acsnano.1c04086}, DOI={10.1021/acsnano.1c04086}, abstractNote={Printed component sizes in electronic circuits are approaching 10 nm, but inherent variability in feature alignment during photolithography poses a fundamental barrier for continued device scaling. Deposition-based self-aligned patterning is being introduced, but nuclei defects remain an overarching problem. This work introduces low-temperature chemically self-aligned film growth via simultaneous thin film deposition and etching in adjacent regions on a nanopatterned surface. During deposition, nucleation defects are avoided in nongrowth regions because deposition reactants are locally consumed via sacrificial etching. For a range of materials and process conditions, thermodynamic modeling confirms that deposition and etching are both energetically favorable. We demonstrate nanoscale patterning of tungsten at 220 °C with simultaneous etching of TiO2. Area selective deposition (ASD) of the sacrificial TiO2 layer produces an orthogonal sequence for self-aligned patterning of two materials on one starting pattern, i.e., TiO2 ASD on SiO2 followed by W ASD on Si-H. Experiments also show capacity for self-aligned dielectric patterning via favorable deposition of AlF3 on Al2O3 at 240 °C with simultaneous atomic layer etching of sacrificial ZnO. Simultaneous deposition and etching provides opportunities for low-temperature bottom-up self-aligned patterning for electronic and other nanoscale systems.}, number={7}, journal={ACS NANO}, publisher={American Chemical Society (ACS)}, author={Song, Seung Keun and Kim, Jung-Sik and Margavio, Hannah R. M. and Parsons, Gregory N.}, year={2021}, month={Jul}, pages={12276–12285} }