Browsing by Author "Walker, Amy V."
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Item Application of Visible-Light Photosensitization to Form Alkyl-Radical-Derived Thin Films on GoldQuarels, Rashanique D.; Zhai, Xianglin; Kuruppu, Neepa; Hedlund, Jenny K.; Ellsworth, Ashley A.; Walker, Amy V.; Garno, Jayne C.; Ragains, Justin R.; Hedlund, Jenny K.; Ellsworth, Ashley A.; Walker, Amy V.Visible-light irradiation of phthalimide esters in the presence of the photosensitizer [Ru(bpy)₃]²⁺ and the stoichiometric reducing agent benzyl nicotinamide results in the formation of alkyl radicals under mild conditions. This approach to radical generation has proven useful for the synthesis of small organic molecules. Herein, we demonstrate for the first time the visible-light photosensitized deposition of robust alkyl thin films on Au surfaces using phthalimide esters as the alkyl radical precursors. In particular, we combine visible-light photosensitization with particle lithography to produce nanostructured thin films, the thickness of which can be measured easily using AFM cursor profiles. Analysis with AFM demonstrated that the films are robust and resistant to mechanical force while contact angle goniometry suggests a multilayered and disordered film structure. Analysis with IRRAS, XPS, and TOF SIMS provides further insights.Item Atomic Layer Deposition Application in Interconnect Technology: From Material Understanding to Area Selective Deposition(December 2021) Hwang, Su Min; Kim, Jiyoung; Kehtarnavaz, Nasser; Quevedo-Lopez, Manuel; Alavrez, Daniel; Wallace, Robert M.; Walker, Amy V.Atomic layer deposition (ALD) technique has been widely employed in the semiconductor industry. As the devices continuously scaling down to sub 3 nm, SiOx and SiNx thin films, for applications such as a spacer or an etch stopper, are expected to satisfy stringent requirements (e.g., precise thickness control, high bulk film density, high wet-etch resistance, conformality, and lowthermal budget) in the current back-end-of-line process. Besides the film qualities, challenges in the current “top-down” approach also need to be addressed to reduce the size of the devices. Moreover, the lack of a fundamental understanding of surface chemistry using in-situ characterization can further impede future interconnect technology. This dissertation focuses on the application of the ALD process for current and future interconnect technology applications. The first study is ALD of high-quality SiOx and SiNx films with lowtemperature feasibility. With the structural modification of conventional Si precursors (e.g., the addition of ligand or substitution of terminating groups), the molecular polarity of precursors is changed, resulting in the improvement of surface reactivities. By leveraging the unique structure of the Si sources, the film deposition at low temperature with enhanced film properties can be achieved. Secondly, this dissertation further identifies the correlation between the metal surface condition and physical/chemical stability of passivation materials in application to the areaselective deposition process. Using in-situ reflectance absorption infrared spectroscopy (RAIRS), X-ray photoelectron spectroscopy (XPS), and high-resolution TEM analysis, the issues arising with poor ALD selectivity are identified. After analyzing the issues, the potential solution to provide a high-quality SAM monolayer is demonstrated. Lastly, a cleaning process using a noble metal cleaning agent, in which a clean metal surface at low temperature (< 200 o C) can be achieved, is developed. The unique cleaning process could pave the way for the implementation of the consecutive organic-free area-selective-deposition process.Item Chemical Bath Deposition of Molybdenum Disulfide and Copper Sulfide Thin Films(2019-05) Orbeck, Jenny K.; 0000-0001-8569-802X (Orbeck, JK); Walker, Amy V.The integration of new technologies into everyday devices requires the development of reliable low-cost methods to deposit semiconductor thin-films. In this work chemical bath deposition (CBD), a solution-based technique, is investigated for the deposition of molybdenum disulfide and copper sulfide thin films on organic substrates, specifically alkanethiolate self-assembled monolayers (SAMs). SAMs serve as useful model organic layers because they are uniform organic layers on the surface and are synthetically flexible. Using Raman spectroscopy and x-ray photoelectron spectroscopy, we demonstrate that by using CBD the deposited MoS₂ polytype can be changed from semiconducting 2H MoS₂ on hydrophobic –CH₃ and –CO₂C₆F₅ terminated self-assembled monolayers (SAMs) to semi-metallic 1T MoS₂ on hydrophilic –OH and –COOH terminated SAMs. The deposition of the different polytypes is controlled by the surface energies of the substrate; high surface energy, hydrophilic substrates stabilize 1T MoS₂ films while 2H MoS₂, which is the thermodynamically stable polytype, is deposited on lower surface energy substrates. Further, the studies show that the deposition occurs via the reaction of ammonium molybdate with hydrogen sulfide produced by the reaction of hydrazine with thioacetamide. The hydrazine then reduces the thiomolybdate ions to molybdenum disulfide. The CBD deposition of copper sulfide is strongly dependent on the bath pH and the terminal group of the SAM. Using thiourea as a sulfur source, it is shown for the first time that the copper sulfide deposit can be changed from covellite, CuS, to chalcocite, Cu2S. In contrast using thioacetamide as a sulfur source the deposited film is always CuS. The selectivity of the deposition is dependent on the SAM terminal group. At pH 9 or less, CuS is preferentially deposited on –CH₃ terminated SAMs. Above pH 9, CuS is preferentially deposited on –COOH terminated SAMs. This is due to three competing processes: the decomposition of the thioacetamide to form sulfide ions, the interaction of the sulfide ions with the SAM terminal groups and the formation of Cu-terminal group complexes.Item Demonstration of POC Biosensor Toward Clinical Translation for Patient Bed-side Monitoring(December 2021) Tanak, Ambalika Sanjeev; Prasad, Shalini; Walker, Amy V.; Muthukumar, Sriram; Sirsi, Shashank; Ardestani Khoubrouy, SoudehThe research presented in this dissertation focuses on developing and characterizing a multiplexed affinity based electrochemical biosensing device toward clinical translation. The goal of this work is to establish a portable POC device for early disease detection across diverse healthcare applications using low sample volume, rapid response time and usability amongst minimally trained individual relying on ASSURED (Affordable, Sensitive, Specific, User friendly, rapid, and Robust, Equipment free and Deliverable to end users) criteria. Primarily, we designed a robust, non-faradaic electrochemical affinity biosensing platform for the rapid assessment of parathyroid hormone (PTH) as a single biosensing system. Unique high density semiconducting nanostructured arrays on a flexible sensing surface were used to create the analytical nanobiosensor. The surface modification technique was specifically designed to improve the interaction of the nanostructure–biological interface to capture the desired PTH level in HS and plasma. This was followed by evaluating the analytical performance of the developed biosensor with clinical rigor. The assay validation results were compared with laboratory standard as reference with results that demonstrated comparable performance with higher accuracy. Next, the scope of the biosensor was expanded to solve a clinically challenging problem of detecting host immune markers for life-threatening sepsis infection. Herein, we demonstrate a first-of-a-kind multiplexed POC biosensing device that simultaneously detects a panel of eight key immune response cytokine biomarkers in sample volume equivalent to two drops of plasma and whole blood within 5 minutes without sample dilution. Moreover, this work focuses on validating the developed biosensing device with LUMINEX standard reference method for clinical translation using nearly 200 patient samples. The DeTecT (Direct Electrochemical Technique Targeting) Sepsis biosensing device is surface engineered with specific capture probes that utilizes EIS to measure the capacitive impedance change reflecting binding interactions between the capture probe and target biomarker enabling multiplexed detection. Specificity of the biosensor was validated using cross-reactive studies, which displayed insignificant interference from non-specific biomarkers. The biosensor also displays stable and repeatable performance. The novelty presented in this research combines the effectiveness of choosing specific host immune response biomarkers for detection of sepsis combined with unique surface modification strategy coupled with EIS technique to enable efficient clinical decision-making process. This unique sensor technology would allow medical practitioners to facilitate targeted interventions for septic patients as a rapid prognostic approach, preventing complications arriving from sepsis.Item From Material Understanding to Volatile Threshold Switches Using Crystalline Zinc Oxide: Selector Device for X-point Memory Application(2020-04-22) Kim, Harrison; Kim, Jiyoung; Walker, Amy V.A cross-point array is considered a promising architecture that accelerates neuro-inspired machine learning algorithms. Leakage current arising from neighboring un/half-selected memory cells is the main source of power dissipation in the cross-point array and it also increases the read/write disturbance when not properly suppressed. Leakage current is considered as one of the main hurdles that must be overcome to increase the density of cross-point memory arrays, where highdensity is essentially required to achieve the neuromorphic network. A filament-type selector has been suggested as a threshold switching selector that holds the potential for applications in largescale integration that reduces read/write disturbance, and power consumption because of its ultralow leakage current compared to other types of threshold switching selectors. This dissertation focuses on the characterization of the surface and interface of crystalline zinc oxide (ZnO) switching layers, to propose a way to mend the common drawbacks associated with the filament-type threshold switching selectors; threshold voltage variability and poor cycling endurance. Initially, a variety of materials characterization techniques, such as Raman, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscope (SEM), four-point probe, Hall measurement, including in-situ electrical monitoring using UHV cluster tool, have been employed to understand the material properties of atomic layer deposited (ALD) crystalline ZnO. Afterward, a technique so-called “super-cycle ALD”, alternating ZnO ALD and Ag metal ALD, to lightly dope ZnO with Ag, has been proposed. Switching parameters are evaluated, however, unstable volatility of silver precursor made it nearly impossible to reproduce the results using ALD. Thus, to lightly dope ZnO with silver, the electrochemical deposition (ECD) process is then adopted as it is highly beneficial in controlling the doping concentration in ZnO with atomic percent precision. ECD process helps in the understanding of volatile switching behavior in lightly doped ZnO with Ag, however, inherently has difficulties in controlling the morphology and thickness. To circumvent the shortcomings associated with both processes, the co-sputtering process (with two different targets sputtered in synchronized phases) has been employed. The significantly improved switching parameters are explained based on Raman, XPS, XRD, AFM, HR-TEM, and semiconductor parameter analyzer.Item Infrared Spectroscopy Studies of Electron Induced Reaction Mechanisms in EUV Photoresists(2019-12) Cabrera, Yasiel; Walker, Amy V.Extreme ultraviolet (EUV) lithography, with approximately 13.5 nm photons is the new standard of the semiconductor industry. The use of EUV photons allows for further miniaturization of integrated circuits, enabling industry and researchers alike to explore the 1 – 10 nm regime. Despite the desire to begin mass producing devices with EUV tools by 2020, a clear direction for the best EUV capable photoresists is not understood. In this dissertation, a novel class photoresist material is investigated to understand key areas of their reaction mechanisms for next-generation photolithography. These photoresists are composed of a hybrid nanocluster architecture with a small HfOₓ core surrounded by methacrylic acid ligand (HfMAA) and can achieve high sensitivity and etch-resistance due to their small molecular nature, high-absorption metal core, and ease of ligand tunability. However, many aspects about their properties and reactivity are still poorly understood. To investigate the reaction mechanisms, the photoresists were probed with a bream of energetic electrons, corresponding to primary and secondary energies produced during EUV ionizations. Their chemical transformation upon electron irradiation, along with the effects of annealing, were tracked using in situ infrared (IR) spectroscopy. After post-application bake (PAB) to 105 °C, the IR spectra show the formation of new Hf-O-Hf bonds through the consumption of terminal hydroxyl groups. This bond formation negatively affects the intrinsic solubility characteristic of the photoresists. Additionally, a crosslinking pathway is initiated by a decarboxylation mechanism of the methacrylate ligands (MAA) under electron irradiation. To understand further the role of secondary electrons in HfMAA, a ligand exchange procedure was employed to change ~20% of the MAA with 4-hydrobenzoic acid (HBA) and phenyl acetic acid (PAA). In situ IR spectroscopy was used to monitor the amount of alkyl CH produced by both 90 and 20 eV electron irradiations. The addition of the co-ligand enhanced the secondary electron sensitivity by 40% when compared to HfMAA. In addition, using mass spectrometry, two different reaction pathways are observed for each co-ligand due to the benzene ring of each ligand decomposes differently. Finally, a number of fundamental studies were performed to investigate EUV/electron-induced resist chemistry in thin-film model systems. Using methacrylic acid (MAA), isobutyric acid (IBA), and 4-hydrobenzoic acid (HBA) as prototypical probe molecules, we find spectroscopic evidence for a decarboxylation mechanism among each of the grafted carboxylate molecules. Differences in selection rules for EUV absorption vs impact ionization for 90 eV electrons are found to play an important role in the reactivity of ligands with different metal centers. Lastly, ab initio model calculations are compared to experimental data and demonstrate their potential use to screen reactivity of different carboxylate ligands and provide validation of first principles method for predicting reactivity of candidate resist chemistries. Additionally, we successfully grafted trivinyl-, dimethylsilamine on SiO₂ to fundamentally study the effect of electron irradiation of organosilane based molecules. Results show with FTIR spectroscopy we can study reactivity of the silicon-vinyl groups by spin coating a thin siloxane based polymer layer on top of the monolayer. We demonstrated interaction between the two layers can occur with electron irradiation through the formation of Si-C and Si-O bonds.Item Law and Disorder: Special Stacking Units—Building the Intergrowth Ce₆ Co₅ Ge₁₆(American Chemical Society, 2019-04-22) Felder, Justin B.; Weiland, Ashley; Hodovanets, H.; McCandless, George T.; Estrada, Tania G.; Martin, Thomas J.; Walker, Amy V.; Paglione, J.; Chan, Julia Y.; 0000-0003-4434-2160 (Chan, JY); 0000-0002-2528-1967 (Felder, JB); 0000-0001-7198-3559 (Weiland, A); 0000-0003-2114-3644 (Walker, AV); Felder, Justin B.; Weiland, Ashley; McCandless, George T.; Estrada, Tania G.; Martin, Thomas J.; Walker, Amy V.; Chan, Julia Y.A new structure type of composition Ce₆ Co₅ Ge₁₆ was grown out of a molten Sn flux. Ce₆ Co₅ Ge₁₆ crystallizes in the orthorhombic space group Cmcm, with highly anisotropic lattice parameters of α = 4.3293(5) Å, b = 55.438(8) Å, and c = 4.3104(4) Å. The resulting single crystals were characterized by X-ray diffraction, and the magnetic and transport properties are presented. The Sn-stabilized structure of Ce₆ Co₅ Ge₁₆ is based on the stacking of disordered Ce cuboctahedra and is an intergrowth of existing structure types including AlB₂ , BaNiSn₃, and AuCu₃. The stacking of structural subunits has previously been shown to be significant in the fields of superconductivity, quantum materials, and optical materials. Herein, we present the synthesis, characterization, and complex magnetic behavior of Ce₆ Co₅ Ge₁₆ at low temperature, including three distinct magnetic transitions. © 2019 American Chemical Society.Item Low-Temperature and Photoactivated CVD on Organic Substrates(2021-12-01T06:00:00.000Z) Salazar, Bryan G.; Walker, Amy V.; Kolodrubetz, Michael; Balkus Jr., Kenneth J.; Gelb, Lev D.; Smaldone, Ronald A.Chemical vapor deposition (CVD) is an attractive technique for depositing metallic thin films on organic substrates. However, CVD often uses temperatures > 500 °C to initiate precursor decomposition and generate highly reactive species. This can be problematic when using attempting to deposit on organic thin films as they can degrade at temperatures < 200 °C. Here we offer an alternative to thermal activation by using photolysis to generate reactive species at room temperature. In this work we monitor decomposition pathways of photoactivated precursors by employing TOF SIMS to identify molecular species remaining on the surface as well as test the integrity of the surface post-deposition. XPS is used to identify organic surface- metal interactions, and finally RGA is used to identify gas-phased decomposition products to further identify photolytic pathways. In identifying the decomposition pathway, we aim to use this understanding to further improve the deposition of metal on organic substrates.Item Partially Fluorinated Oxo-Alkoxide Tungsten(VI) Complexes as Precursors for Deposition of WOx Nanomaterials(Royal Society of Chemistry) Bonsu, R. O.; Kim, H.; O'Donohue, C.; Korotkov, R. Y.; McClain, K. R.; Abboud, K. A.; Ellsworth, Ashley A.; Walker, Amy V.; Anderson, T. J.; McElwee-White, L.; 0000 0001 3758 9240 (Walker, AV)The partially fluorinated oxo-alkoxide tungsten(VI) complexes WO(OR) 4 [4; R = C(CH3)2CF3, 5; R = C(CH3)(CF3)2] have been synthesized as precursors for chemical vapour deposition (CVD) of WOx nanocrystalline material. Complexes 4 and 5 were prepared by salt metathesis between sodium salts of the fluoroalkoxides and WOCl4. Crystallographic structure analysis allows comparison of the bonding in 4 and 5 as the fluorine content of the fluoroalkoxide ligands is varied. Screening of 5 as a CVD precursor by mass spectrometry and thermogravimetric analysis was followed by deposition of WOx nanorods.Item Phase Transition of Community Detection Under Efficient Algorithms, Expressive Generative Models, and Confidentiality Constraints(December 2022) Esmaeili, Mohammad 1991-; Nosratinia, Aria; Walker, Amy V.; Faragó, András; Busso-Recabarren, Carlos A.; Kehtarnavaz, NasserWe formulate a semi-definite relaxation for the maximum likelihood estimation of node labels, subject to observing both graph and non-graph data. This formulation is distinct from the semidefinite programming solution of standard community detection, but maintains its desirable properties. We calculate the exact recovery threshold for three types of non- graph information, which are called side information: partially revealed labels, noisy labels, as well as multiple observations (features) per node with arbitrary but finite cardinality. We find that semidefinite programming has the same exact recovery threshold in the presence of side information as maximum likelihood with side information. Empirical observations suggest that in practice, community membership does not completely explain the dependency between the edges of an observation graph. The residual dependence of the graph edges are modeled in this dissertation, to first order, by auxiliary node latent variables that affect the statistics of the graph edges but carry no information about the communities of interest. We then study community detection in graphs obeying the stochastic block model and censored block model with auxiliary latent variables. We analyze the conditions for exact recovery when these auxiliary latent variables are unknown, representing unknown nuisance parameters or model mismatch. We also analyze exact recovery when these secondary latent variables have been either fully or partially revealed. Finally, we propose a semidefinite programming algorithm for recovering the desired labels when the secondary labels are either known or unknown. We show that exact recovery is possible by semidefinite programming down to the respective maximum likelihood exact recovery threshold. Releasing graph structures containing nodes with multiple latent variables might cause privacy issues and confidential information leakage of the users. This dissertation investigates the confidentiality in community detection in networks with multiple latent variables. Focusing on stochastic block model and censored block model with multiple latent variables, we address the leakage of confidential information by changing the connectivity of nodes. To this end, we first propose a new metric for evaluation of confidentiality based on Chernoff- Hellinger divergence. An optimization is introduced to minimize the required changes on the edges of the graph realization.Item Photochemical CVD of Ru on Functionalized Self-Assembled Monolayers from Organometallic Precursors(American Institute of Physics Inc, 2018-08-20) Johnson, K. R.; Rodriguez, Paul Arevalo; Brewer, C. R.; Brannaka, J. A.; Shi, Zhiwei; Yang, Jing; Salazar, Brian; McElwee-White, L.; Walker, Amy V.; 0000 0001 3758 9240 (Walker, AV); 0000-0003-3079-7367 (Salazar, B); Rodriguez, Paul Arevalo; Shi, Zhiwei; Yang, Jing; Salazar, Brian; Walker, Amy V.Chemical vapor deposition (CVD) is an attractive technique for the metallization of organic thin films because it is selective and the thickness of the deposited film can easily be controlled. However, thermal CVD processes often require high temperatures which are generally incompatible with organic films. In this paper, we perform proof-of-concept studies of photochemical CVD to metallize organic thin films. In this method, a precursor undergoes photolytic decomposition to generate thermally labile intermediates prior to adsorption on the sample. Three readily available Ru precursors, CpRu(CO)₂Me, (η³-allyl)Ru(CO)₃Br, and (COT)Ru(CO)₃, were employed to investigate the role of precursor quantum yield, ligand chemistry, and the Ru oxidation state on the deposition. To investigate the role of the substrate chemistry on deposition, carboxylic acid-, hydroxyl-, and methyl-terminated self-assembled monolayers were used. The data indicate that moderate quantum yields for ligand loss (φ ≥ 0.4) are required for ruthenium deposition, and the deposition is wavelength dependent. Second, anionic polyhapto ligands such as cyclopentadienyl and allyl are more difficult to remove than carbonyls, halides, and alkyls. Third, in contrast to the atomic layer deposition, acid-base reactions between the precursor and the substrate are more effective for deposition than nucleophilic reactions. Finally, the data suggest that selective deposition can be achieved on organic thin films by judicious choice of precursor and functional groups present on the substrate. These studies thus provide guidelines for the rational design of new precursors specifically for selective photochemical CVD on organic substrates.Item Polytype Control of MoS₂ Using Chemical Bath Deposition(American Institute of Physics Inc., 2019-05-01) Hedlund, Jenny K.; Walker, Amy V.; 0000-0003-2114-3644 (Walker, AV); Hedlund, Jenny K.; Walker, Amy V.Molybdenum disulfide (MoS₂) has a wide range of applications from electronics to catalysis. While the properties of single-layer and multilayer MoS₂ films are well understood, controlling the deposited MoS₂ polytype remains a significant challenge. In this work, we employ chemical bath deposition, an aqueous deposition technique, to deposit large area MoS₂ thin films at room temperature. Using Raman spectroscopy and x-ray photoelectron spectroscopy, we show that the deposited MoS₂ polytype can be changed from semiconducting 2H MoS₂ on hydrophobic -CH₃ and -CO₂C₆F₅ terminated self-assembled monolayers (SAMs) to semimetallic 1T MoS₂ on hydrophilic -OH and -COOH terminated SAMs. The data suggest that the deposition of MoS₂ polytypes is controlled by the substrate surface energy. High surface energy substrates stabilize 1T MoS₂ films, while 2H MoS₂ is deposited on lower surface energy substrates. This effect appears to be general enabling the deposition of different MoS₂ polytypes on a wide range of substrates. ©2019 Author(s).Item Room Temperature Atomic Layerlike Deposition of ZnS on Organic Thin Films: Role of Substrate Functional Groups and Precursors(AVS Science and Technology Society) Shi, Z.; Walker, Amy V.; 0000 0001 3758 9240 (Walker, AV)The room temperature atomic layerlike deposition (ALLD) of ZnS on functionalized self-assembled monolayers (SAMs) was investigated, using diethyl zinc (DEZ) and in situ generated H₂S as reactants. Depositions on SAMs with three different terminal groups, -CH₃, -OH, and -COOH, were studied. It was found that the reaction of DEZ with the SAM terminal group is critical in determining the film growth rate. Little or no deposition is observed on -CH₃ terminated SAMs because DEZ does not react with the methyl terminal group. ZnS does deposit on both -OH and -COOH terminated SAMs, but the grow rate on -COOH terminated SAMs is ∼10% lower per cycle than on -OH terminated SAMs. DEZ reacts with the hydroxyl group on -OH terminated SAMs, while on -COOH terminated SAMs it reacts with both the hydroxyl and carbonyl bonds of the terminal groups. The carbonyl reaction is found to lead to the formation of ketones rather than deposition of ZnS, lowering the growth rate on -COOH terminated SAMs. SIMS spectra show that both -OH and -COOH terminated SAMs are covered by the deposited ZnS layer after five ALLD cycles. In contrast to ZnO ALLD where the composition of the film differs for the first few layers on -COOH and -OH terminated SAMs, the deposited film composition is the same for both -COOH and -OH terminated SAMs. The deposited film is found to be Zn-rich, suggesting that the reaction of H₂S with the Zn-surface adduct may be incomplete.Item Synthetic Design of Cerium-Based Intermetallics(2021-05-01T05:00:00.000Z) Weiland, Ashley; Chan, Julia; Xuan, Zhenyu; Zheng, Jie; Nielsen, Steven O.; Walker, Amy V.Ce-based highly correlated systems are of interest due to Ce3+ (S=1/2) providing an ideal f-electron system to study the interplay of localized magnetic moments and conduction electrons. The growth of high-quality single crystals is of utmost importance to ensure the determination of intrinsic anisotropic properties. This dissertation presents the single crystal growth and d etailed characterization of Ce-containing intermetallics. Motivated by the search for new spintronic devices based on topological materials, the first study highlights the incorporation of Bi in the topological parent compound, CeSbTe. Sb net containing CeSbTe has been studied to show the interplay of magnetism and topology. Inserting Bi, a larger element, provides the opportunity to change the Fermi surface while preserving topologically relevant features. We show the band structure engineering of potential topological materials LnSb1-xBixTe (Ln = La, Ce, Pr; x ~ 0.2) and CeBiTe. Continuing our search for novel quantum materials, our elucidation of crystal growth parameters of Ce-based intermetallics, led to the identification of a new intermetallic homologous series An+1MnX3n+1 (A = rare earth; M = transition metal; X = tetrels; n = 1 – 6) built up of structural subunits such as AlB2, AuCu3, and BaNiSn3. The homologous series serves as a model system for studying the coupling between localized f-electrons and conduction electrons. Additionally, the stacking of heterostructural subunits is an exciting way to modify physical properties of related phases, highlighting the importance of structural building blocks as a new avenue to study magnetism and topology. Crystal growth, detailed single crystal structural modeling, and magnetic and transport properties of Ce5Co4+xGe13-ySny (n = 4), Ce6Co5+xGe16-ySny (n = 5), and Ce7Co6+xGe19-ySny (n = 6), are presented. The similarities between the synthetic profiles used to grow n = 4 – 6 brought about new questions which led to our work investigating phase formation. Finally, the process for designing in situ synchrotron experiments, including a new sample environment and furnace apparatus for the use with flux grown intermetallics, is presented.Item Toward Understanding Weak Matrix Effects in TOF SIMS(American Vacuum Society) Gelb, Lev D.; Walker, Amy V.; 0000 0001 3758 9240 (Walker, AV); 0000-0003-0291-5098 (Gelb, LD); Gelb, Lev D.; Walker, Amy V.Chemical imaging methods, including imaging mass spectrometry, are increasingly used for the analysis of samples ranging from biological tissues to electronic devices. A barrier to wider adoption of imaging mass spectrometry is the presence of matrix effects which complicate quantitative analysis. Interactions between an analyte molecule and its surroundings (the "matrix") can substantially alter both the yield and type of ions observed. Furthermore, such "intrinsic" effects can be confused with nonlinear response due to detector saturation and other instrument-related complications. As a result, quantitative analyses of time-of-flight secondary ion mass spectrometry (TOF SIMS) data that attempt to account for matrix effects are rare. The authors discuss analysis of such data using maximum a posteriori reconstruction based on physically motivated models, and present progress toward the quantitative extraction of chemical concentration profiles and component spectra in the presence of matrix effects, using mixed self- assembled alkanethiolate monolayers as a test system. The authors demonstrate that the incorporation of matrix effects to lowest order using a series-expansion approach is an effective strategy and that doing so provides improved quantitative performance in measuring surface compositions and can also yield information about interactions between species during the SIMS process. Published by the AVS.