@article{pham_gai_rochester_dycus_lebeau_manga_corral_2023, title={Thermodynamic assessment within the Zr-B-C-O quaternary system}, ISSN={["1551-2916"]}, DOI={10.1111/jace.18958}, abstractNote={Abstract Thermodynamic modeling of Zr–B–C–O quaternary system is conducted within the CALPHAD framework by employing data obtained from first‐principle calculations and literature. The lower order binary B–O is assessed in this work by estimating the thermodynamic properties of stable solid phases of B 2 O 3 and B 6 O and by estimating the gas and liquid phases. First‐principle calculations, in conjunction with special quasirandom structure were used to predict enthalpies of mixing for the ternary solid‐solution phase of FCC‐Zr(C, O). The calculated results were used to optimize the model parameters pertaining to the cubic phase, which is described by a two‐sublattice model. The modeled Zr–C–O ternary phase diagrams calculated at 1923 and 2273 K under ambient pressure and 4 Pa, respectively, are in agreement with experimental phase diagrams.}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={Pham, David and Gai, Fangyuan and Rochester, Jacob and Dycus, Joseph H. and LeBeau, James M. and Manga, Venkateswara Rao and Corral, Erica L.}, year={2023}, month={Jan} }
 @article{rathkanthiwar_dycus_mita_kirste_tweedie_collazo_sitar_2022, title={Pseudomorphic growth of thick Al0.6Ga0.4N epilayers on AlN substrates}, volume={120}, ISSN={["1077-3118"]}, DOI={10.1063/5.0092937}, abstractNote={We report on the absence of strain relaxation mechanism in Al0.6Ga0.4N epilayers grown on (0001) AlN substrates for thickness as large as 3.5  μm, three-orders of magnitude beyond the Matthews–Blakeslee critical thickness for the formation of misfit dislocations (MDs). A steady-state compressive stress of 3–4 GPa was observed throughout the AlGaN growth leading to a large lattice bow (a radius of curvature of 0.5 m−1) for the thickest sample. Despite the large lattice mismatch-induced strain energy, the epilayers exhibited a smooth and crack-free surface morphology. These results point to the presence of a large barrier for nucleation of MDs in Al-rich AlGaN epilayers. Compositionally graded AlGaN layers were investigated as potential strain relief layers by the intentional introduction of MDs. While the graded layers abetted MD formation, the inadequate length of these MDs correlated with insignificant strain relaxation. This study emphasizes the importance of developing strain management strategies for the implementation of the single-crystal AlN substrate platform for III-nitride deep-UV optoelectronics and power electronics.}, number={20}, journal={APPLIED PHYSICS LETTERS}, author={Rathkanthiwar, Shashwat and Dycus, J. Houston and Mita, Seiji and Kirste, Ronny and Tweedie, James and Collazo, Ramon and Sitar, Zlatko}, year={2022}, month={May} }
 @article{khachariya_mita_reddy_dangi_dycus_bagheri_breckenridge_sengupta_rathkanthiwar_kirste_et al._2022, title={Record >10 MV/cm mesa breakdown fields in Al0.85Ga0.15N/Al0.6Ga0.4N high electron mobility transistors on native AlN substrates}, volume={120}, ISSN={["1077-3118"]}, DOI={10.1063/5.0083966}, abstractNote={The ultra-wide bandgap of Al-rich AlGaN is expected to support a significantly larger breakdown field compared to GaN, but the reported performance thus far has been limited by the use of foreign substrates. In this Letter, the material and electrical properties of Al0.85Ga0.15N/Al0.6Ga0.4N high electron mobility transistors (HEMT) grown on a 2-in. single crystal AlN substrate are investigated, and it is demonstrated that native AlN substrates unlock the potential for Al-rich AlGaN to sustain large fields in such devices. We further study how Ohmic contacts made directly to a Si-doped channel layer reduce the knee voltage and increase the output current density. High-quality AlGaN growth is confirmed via scanning transmission electron microscopy, which also reveals the absence of metal penetration at the Ohmic contact interface and is in contrast to established GaN HEMT technology. Two-terminal mesa breakdown characteristics with 1.3 μm separation possess a record-high breakdown field strength of ∼11.5 MV/cm for an undoped Al0.6Ga0.4N-channel layer. The breakdown voltages for three-terminal devices measured with gate-drain distances of 4 and 9 μm are 850 and 1500 V, respectively.}, number={17}, journal={APPLIED PHYSICS LETTERS}, author={Khachariya, Dolar and Mita, Seiji and Reddy, Pramod and Dangi, Saroj and Dycus, J. Houston and Bagheri, Pegah and Breckenridge, M. Hayden and Sengupta, Rohan and Rathkanthiwar, Shashwat and Kirste, Ronny and et al.}, year={2022}, month={Apr} }
 @article{nozariasbmarz_dycus_cabral_flack_krasinski_lebeau_vashaee_2021, title={Efficient self-powered wearable electronic systems enabled by microwave processed thermoelectric materials}, volume={283}, ISSN={["1872-9118"]}, DOI={10.1016/j.apenergy.2020.116211}, abstractNote={The integrated body sensor networks are expected to dominate the future of healthcare, making a critical paradigm shift that will support people in the comfort and security of their own homes. Thermoelectric generators, in this regard, can play a crucial role as they can steadily generate electricity from body heat and enable self-powered wearable or implantable medical, health, and sports devices. This work provides a comprehensive analysis of the operation and the optimization of wearable thermoelectric generators under different human body conditions. Thermoelectric design principles, wearable system considerations, and a novel method to synthesize the materials specially designed for body heat harvesting are presented. The limitations of the materials and systems for wearable applications are deliberated in detail, and the feasibility of eliminating the heatsink for enhancing body comfort is examined. N-type Bi2Te3-xSex was synthesized using a novel approach based on field-induced decrystallization by microwave radiation to achieve the optimum properties. This method resulted in amorphous-crystalline nanocomposites with simultaneously large thermopower and small thermal conductivity around the body temperature. Thermoelectric generators were fabricated from the optimized materials and packaged in flexible elastomers. The devices generated up to 150% higher voltage and 600% more power on the body compared to the commercial ones and, so far, are the best in class for body heat harvesting in wearable applications.}, journal={APPLIED ENERGY}, author={Nozariasbmarz, Amin and Dycus, J. Houston and Cabral, Matthew J. and Flack, Chloe M. and Krasinski, Jerzy S. and LeBeau, James M. and Vashaee, Daryoosh}, year={2021}, month={Feb} }
 @article{gai_dycus_lebeau_walker_corral_2021, title={Instantaneous nanowelding of ultra-high temperature ceramics for hypersonics}, ISSN={["1551-2916"]}, DOI={10.1111/jace.17866}, abstractNote={Abstract Ultra‐high temperature ceramics (UHTCs) are a group of advanced ceramic materials that possess excellent high temperature capabilities, which make them especially suitable for extreme environment engineering applications. As an effective assembling method, joining is frequently required for fabricating sophisticated structures for such applications due to the excessive challenges and costs in producing near‐net shapes. Here, we introduce a promising new joining technique to effectively join UHTCs called Instantaneous Nanowelding , which uses direct electric current assisted rapid Joule heating to instantaneously bond hafnium diboride (HfB 2 ) to zirconium diboride (ZrB 2 ) in 1 s down to atomic scale. Our approach is analogous to high temperature spot welding, and the entire process is complete in 10 min, and the instant diffusion occurs in 1 s. Seamless HfB 2 /ZrB 2 interfaces are formed at 1750 for a duration of 1 s. A series of characterizations are done at the interfaces using techniques including SEM, WDS, EBSD, and S/TEM to observe Zr x Hf 1− x B 2 solid solution formation. Highly coherent transition with perfect lattice alignment at atomic scale from ZrB 2 to HfB 2 is observed using S/TEM, meaning that the two materials are brought to atomic contact.}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={Gai, Fangyuan and Dycus, Joseph Houston and LeBeau, James M. and Walker, Luke S. and Corral, Erica L.}, year={2021}, month={May} }
 @article{mirrielees_dycus_baker_reddy_collazo_sitar_lebeau_irving_2021, title={Native oxide reconstructions on AlN and GaN (0001) surfaces}, volume={129}, ISSN={["1089-7550"]}, DOI={10.1063/5.0048820}, abstractNote={Properties of AlN/GaN surfaces are important for realizing the tunability of devices, as the presence of surface states contributes to Fermi level pinning. This pinning can influence the performance of high electron mobility transistors and is also important for passivation of the surface when developing high-power electronic devices. It is widely understood that both AlN and GaN surfaces oxidize. Since there are many possible reconstructions for each surface, it is a challenge to identify the relevant surface reconstructions in advance of a detailed simulation. Because of this, different approaches are often employed to down select initial structures to reduce the computational load. These approaches usually rely on either electron counting rules or oxide stoichiometry, as both of these models tend to lead to structures that are energetically favorable. Here we explore models from these approaches but also explore a reconstruction of the (0001) surface directly observed using scanning transmission electron microscopy with predictive density functional theory simulations. Two compositions of the observed surface reconstruction—one which obeys oxide stoichiometry and one which is cation deficient and obeys electron counting—are compared to reconstructions from the previous work. Furthermore, surface states are directly calculated using hybrid exchange-correlation functionals that correct for the underestimation of the bandgaps in AlN and GaN and improve the predicted positions of surface states within the gap. It is found that cation deficiency in the observed reconstruction yields surface states consistent with the experiment. Based on all of these results, we provide insight into the observed properties of oxidized AlGaN surfaces.}, number={19}, journal={JOURNAL OF APPLIED PHYSICS}, author={Mirrielees, Kelsey J. and Dycus, J. Houston and Baker, Jonathon N. and Reddy, Pramod and Collazo, Ramon and Sitar, Zlatko and LeBeau, James M. and Irving, Douglas L.}, year={2021}, month={May} }
 @article{nozariasbmarz_suarez_dycus_cabral_lebeau_ozturk_vashaee_2020, title={Thermoelectric generators for wearable body heat harvesting: Material and device concurrent optimization}, volume={67}, ISSN={["2211-3282"]}, DOI={10.1016/j.nanoen.2019.104265}, abstractNote={Body heat harvesting systems based on thermoelectric generators (TEGs) can play a significant role in wearable electronics intended for continuous, long-term health monitoring. However, to date, the harvested power density from the body using TEGs is limited to a few micro-watts per square centimeter, which is not sufficient to turn on many wearables. The thermoelectric materials research has been mainly focused on enhancing the single parameter zT, which is insufficient to meet the requirements for wearable applications. To develop TEGs that work effectively in wearable devices, one has to consider the material, device, and system requirements concurrently. Due to the lack of an efficient heatsink and the skin thermal resistance, a key challenge to achieving this goal is to design systems that maximize the temperature differential across the TEG while not compromising the body comfort. This requires favoring approaches that deliver the largest possible device thermal resistance relative to the external parasitic resistances. Therefore, materials with low thermal conductivity are critically important to maximize the temperature gradient. Also, to achieve a high boost converter efficiency, wearable TEGs need to have the highest possible output voltage, which calls for a high Seebeck coefficient. At the device level, dimensions of the legs (length versus the base area) and fill factor are both critical parameters to ensure that the parasitic thermal resistances are again negligible compared to the resistance of the module itself. In this study, the concurrent impact of material and device parameters on the efficiency of wearable TEGs is considered. Nanocomposite thermoelectric materials based on bismuth telluride alloys were synthesized using microwave processing and optimized to meet the requirements of wearable TEGs. Microwave energy decrystallized the material leading to a strong reduction of the thermal conductivity while maintaining a high zT at the body temperature. A comprehensive quasi-3D analytical model was developed and used to optimize the material and device parameters. The nanocomposite TEG produced 44 μW/cm2 under no air flow condition, and 156.5 μW/cm2 under airflow. In comparison to commercial TEGs tested under similar conditions, the nanocomposite based TEGs exhibited 4–7 times higher power density on the human body depending on the convective cooling conditions.}, journal={NANO ENERGY}, author={Nozariasbmarz, Amin and Suarez, Francisco and Dycus, J. Houston and Cabral, Matthew J. and LeBeau, James M. and Ozturk, Mehmet C. and Vashaee, Daryoosh}, year={2020}, month={Jan} }
 @article{dycus_washiyama_eldred_guan_kirste_mita_sitar_collazo_lebeau_2019, title={The role of transient surface morphology on composition control in AlGaN layers and wells}, volume={114}, ISSN={["1077-3118"]}, DOI={10.1063/1.5063933}, abstractNote={The mechanisms governing “compositional pulling” during the growth of AlxGa1−xN wells are investigated. Gallium-rich AlxGa1−xN wells grown on high dislocation density AlN/sapphire templates exhibit asymmetric and diffuse composition profiles, while those grown on low dislocation density native AlN substrates do not. Furthermore, strain in all AlxGa1−xN wells is found to be pseudomorphic, ruling it out as the dominating driving force. Rather, the high threading dislocation density of the AlN template is considered to play the defining role. We propose that a transient surface morphology is introduced during dislocation mediated spiral growth, which, in conjunction with process supersaturation, determines the Ga incorporation. These findings provide insights into compositional pulling in high Ga content AlxGa1−xN grown on AlN and provide a route to grow thicker wells with very abrupt interfaces on native AlN substrates.The mechanisms governing “compositional pulling” during the growth of AlxGa1−xN wells are investigated. Gallium-rich AlxGa1−xN wells grown on high dislocation density AlN/sapphire templates exhibit asymmetric and diffuse composition profiles, while those grown on low dislocation density native AlN substrates do not. Furthermore, strain in all AlxGa1−xN wells is found to be pseudomorphic, ruling it out as the dominating driving force. Rather, the high threading dislocation density of the AlN template is considered to play the defining role. We propose that a transient surface morphology is introduced during dislocation mediated spiral growth, which, in conjunction with process supersaturation, determines the Ga incorporation. These findings provide insights into compositional pulling in high Ga content AlxGa1−xN grown on AlN and provide a route to grow thicker wells with very abrupt interfaces on native AlN substrates.}, number={3}, journal={APPLIED PHYSICS LETTERS}, author={Dycus, J. Houston and Washiyama, Shun and Eldred, Tim B. and Guan, Yan and Kirste, Ronny and Mita, Seiji and Sitar, Zlatko and Collazo, Ramon and LeBeau, James M.}, year={2019}, month={Jan} }
 @article{pham_dycus_lebeau_manga_muralidharan_corral_2019, title={Thermochemical model on the carbothermal reduction of oxides during spark plasma sintering of zirconium diboride}, volume={102}, ISSN={["1551-2916"]}, DOI={10.1111/jace.15911}, abstractNote={Abstract Carbon was used to reduce oxides in spark plasma sintered ZrB 2 ultra‐high temperature ceramics. A thermodynamic model was used to evaluate the reducing reactions to remove B 2 O 3 and ZrO 2 from the powder. Powder oxygen content was measured and carbon additions of 0.5 and 0.75 wt% were used. A C–ZrO 2 pseudo binary diagram, ZrO 2 –B 2 O 3 –C pseudo ternaries, and Zr–C–O potential phase diagrams were generated to show how the reactions can be related to an open system experiment in the tube furnace. Scanning transmission electron microscopy identified impurity phases composed of amorphous Zr–B–O with lamellar BN and a Zr–C–O ternary model was calculated under SPS sintering conditions at 1900°C and 6 Pa to understand how oxides can be retained in the microstructure.}, number={2}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={Pham, David and Dycus, Joseph H. and LeBeau, James M. and Manga, Venkateswara R. and Muralidharan, Krishna and Corral, Erica L.}, year={2019}, month={Feb}, pages={757–767} }
 @article{xu_dycus_lebeau_2018, title={Numerical modeling of specimen geometry for quantitative energy dispersive X-ray spectroscopy}, volume={184}, ISSN={["1879-2723"]}, DOI={10.1016/j.ultramic.2017.08.015}, abstractNote={Transmission electron microscopy specimens typically exhibit local distortion at thin foil edges, which can influence the absorption of X-rays for quantitative energy dispersive X-ray spectroscopy (EDS). Here, we report a numerical, three-dimensional approach to model the geometry of general specimens and its influence on quantification when using single and multiple detector configurations. As a function of specimen tilt, we show that the model correctly predicts the asymmetric nature of X-ray counts and ratios. When using a single detector, we show that complex specimen geometries can introduce significant uncertainty in EDS quantification. Further, we show that this uncertainty can be largely negated by collection with multiple detectors placed symmetrically about the sample such as the FEI Super-X configuration. Based on guidance provided by the model, we propose methods to reduce quantification error introduced by the sample shape. The source code is available at https://github.com/subangstrom/superAngle.}, journal={ULTRAMICROSCOPY}, author={Xu, W. and Dycus, J. H. and LeBeau, J. M.}, year={2018}, month={Jan}, pages={100–108} }
 @article{dycus_lebeau_2017, title={A reliable approach to prepare brittle semiconducting materials for cross-sectional transmission electron microscopy}, volume={268}, ISSN={["1365-2818"]}, DOI={10.1111/jmi.12601}, abstractNote={Here, we present a sample preparation approach that simplifies the thinning of very brittle wide bandgap semiconducting materials in cross‐section geometry for (scanning) transmission electron microscopy. Using AlN thin films grown on sapphire and AlN substrates as case studies, we demonstrate that high‐quality samples can be routinely prepared while greatly reducing the preparation time and consumables cost. The approach removes the sample preparation barrier to studying a wide variety of materials by electron microscopy.}, number={3}, journal={JOURNAL OF MICROSCOPY}, author={Dycus, J. H. and Lebeau, J. M.}, year={2017}, month={Dec}, pages={225–229} }
 @article{xu_dycus_sang_lebeau_2016, title={A numerical model for multiple detector energy dispersive X-ray spectroscopy in the transmission electron microscope}, volume={164}, ISSN={["1879-2723"]}, DOI={10.1016/j.ultramic.2016.02.004}, abstractNote={Here we report a numerical approach to model a four quadrant energy dispersive X-ray spectrometer in the transmission electron microscope. The model includes detector geometries, specimen position and absorption, shadowing by the holder, and filtering by the Be carrier. We show that this comprehensive model accurately predicts absolute counts and intensity ratios as a function of specimen tilt and position. We directly compare the model to experimental results acquired with a FEI Super-X EDS four quadrant detector. The contribution from each detector to the sum is investigated. The program and source code can be downloaded from https://github.com/subangstrom/superAngle.}, journal={ULTRAMICROSCOPY}, author={Xu, W. and Dycus, J. H. and Sang, X. and LeBeau, J. M.}, year={2016}, month={May}, pages={51–61} }
 @article{nozariasbmarz_roy_zamanipour_dycus_cabral_lebeau_krasinski_vashaee_2016, title={Comparison of thermoelectric properties of nanostructured Mg2Si, FeSi2, SiGe, and nanocomposites of SiGe-Mg2Si, SiGe-FeSi2}, volume={4}, ISSN={["2166-532X"]}, DOI={10.1063/1.4966138}, abstractNote={Thermoelectric properties of nanostructured FeSi2, Mg2Si, and SiGe are compared with their nanocomposites of SiGe–Mg2Si and SiGe–FeSi2. It was found that the addition of silicide nanoinclusions to SiGe alloy maintained or increased the power factor while further reduced the thermal conductivity compared to the nanostructured single-phase SiGe alloy. This resulted in ZT enhancement of Si0.88Ge0.12–FeSi2 by ∼30% over the broad temperature range of 500-950 °C compared to the conventional Si0.80Ge0.20 alloy. The Si0.88Ge0.12–Mg2Si nanocomposite showed constantly increasing ZT versus temperature up to 950 °C (highest measured temperature) reaching ZT ∼ 1.3. These results confirm the concept of silicide nanoparticle-in-SiGe-alloy proposed earlier by Mingo et al. [Nano Lett. 9, 711–715 (2009)].}, number={10}, journal={APL MATERIALS}, author={Nozariasbmarz, Amin and Roy, Palash and Zamanipour, Zahra and Dycus, J. Houston and Cabral, Matthew J. and LeBeau, James M. and Krasinski, Jerzy S. and Vashaee, Daryoosh}, year={2016}, month={Oct} }
 @article{dycus_xu_sang_d'alfonso_chen_weyland_allen_findlay_lebeau_2016, title={Influence of experimental conditions on atom column visibility in energy dispersive X-ray spectroscopy}, volume={171}, journal={Ultramicroscopy}, author={Dycus, J. H. and Xu, W. and Sang, X. and D'Alfonso, A. J. and Chen, Z. and Weyland, M. and Allen, L. J. and Findlay, S. D. and LeBeau, J. M.}, year={2016}, pages={1–7} }
 @article{pham_dycus_lebeau_manga_muralidharan_corral_2016, title={Processing Low-Oxide ZrB2 Ceramics with High Strength Using Boron Carbide and Spark Plasma Sintering}, volume={99}, ISSN={["1551-2916"]}, DOI={10.1111/jace.14253}, abstractNote={A phase diagram-assisted powder processing approach is shown to produce low-oxygen (0.06 wt%O) ZrB2 ceramics using minimal B4C additions (0.25 wt%) and spark plasma sintering. Scanning electron microscopy and scanning transmission electron microscopy with elemental spectroscopy are used to identify “trash collector” oxides. These “trash collector” oxides are composed of manufacturer metal powder impurities that form discreet oxide particles due to the absence of standard Zr–B oxides found in high oxygen samples. A preliminary Zr–B–C–O quaternary thermodynamic database developed as a part of this work was used to calculate the ZrO2–B4C pseudobinary phase diagram and ZrB2–ZrO2–B4C pseudoternary phase diagrams. We use the calculated equilibrium phase diagrams to characterize the oxide impurities and show the direct reaction path that allows for the formation of ZrB2 with an oxygen content of 0.06 wt%, fine grains (3.3 μm) and superior mechanical properties (flexural strength of 660 MPa).}, number={8}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={Pham, David and Dycus, Joseph Houston and LeBeau, James M. and Manga, Venkateswara R. and Muralidharan, Krishna and Corral, Erica L.}, year={2016}, month={Aug}, pages={2585–2592} }
 @article{chen_weyland_sang_xu_dycus_lebeau_d'alfonso_allen_findlay_2016, title={Quantitative atomic resolution elemental mapping via absolute-scale energy dispersive X-ray spectroscopy}, volume={168}, ISSN={["1879-2723"]}, DOI={10.1016/j.ultramic.2016.05.008}, abstractNote={Quantitative agreement on an absolute scale is demonstrated between experiment and simulation for two-dimensional, atomic-resolution elemental mapping via energy dispersive X-ray spectroscopy. This requires all experimental parameters to be carefully characterized. The agreement is good, but some discrepancies remain. The most likely contributing factors are identified and discussed. Previous predictions that increasing the probe forming aperture helps to suppress the channelling enhancement in the average signal are confirmed experimentally. It is emphasized that simple column-by-column analysis requires a choice of sample thickness that compromises between being thick enough to yield a good signal-to-noise ratio while being thin enough that the overwhelming majority of the EDX signal derives from the column on which the probe is placed, despite strong electron scattering effects.}, journal={ULTRAMICROSCOPY}, author={Chen, Z. and Weyland, M. and Sang, X. and Xu, W. and Dycus, J. H. and LeBeau, J. M. and D'Alfonso, A. J. and Allen, L. J. and Findlay, S. D.}, year={2016}, month={Sep}, pages={7–16} }
 @article{dycus_xu_lichtenwalner_hull_palmour_lebeau_2016, title={Structure and chemistry of passivated SiC/SiO2 interfaces}, volume={108}, ISSN={["1077-3118"]}, DOI={10.1063/1.4951677}, abstractNote={Here, we report on the chemistry and structure of 4H-SiC/SiO2 interfaces passivated either by nitric oxide annealing or Ba deposition. Using aberration corrected scanning transmission electron microscopy and spectroscopy, we find that Ba and N remain localized at SiC/SiO2 interface after processing. Further, we find that the passivating species can introduce significant changes to the near-interface atomic structure of SiC. Specifically, we quantify significant strain for nitric oxide annealed sample where Si dangling bonds are capped by N. In contrast, strain is not observed at the interface of the Ba treated samples. Finally, we place these results in the context of field effect mobility.}, number={20}, journal={APPLIED PHYSICS LETTERS}, author={Dycus, J. Houston and Xu, Weizong and Lichtenwalner, Daniel J. and Hull, Brett and Palmour, John W. and LeBeau, James M.}, year={2016}, month={May} }
 @article{dycus_harris_sang_fancher_findlay_oni_chan_koch_jones_allen_et al._2015, title={Accurate Nanoscale Crystallography in Real-Space Using Scanning Transmission Electron Microscopy}, volume={21}, ISSN={["1435-8115"]}, DOI={10.1017/s1431927615013732}, abstractNote={Abstract Here, we report reproducible and accurate measurement of crystallographic parameters using scanning transmission electron microscopy. This is made possible by removing drift and residual scan distortion. We demonstrate real-space lattice parameter measurements with <0.1% error for complex-layered chalcogenides Bi2Te3, Bi2Se3, and a Bi2Te2.7Se0.3 nanostructured alloy. Pairing the technique with atomic resolution spectroscopy, we connect local structure with chemistry and bonding. Combining these results with density functional theory, we show that the incorporation of Se into Bi2Te3 causes charge redistribution that anomalously increases the van der Waals gap between building blocks of the layered structure. The results show that atomic resolution imaging with electrons can accurately and robustly quantify crystallography at the nanoscale.}, number={4}, journal={MICROSCOPY AND MICROANALYSIS}, author={Dycus, J. Houston and Harris, Joshua S. and Sang, Xiahan and Fancher, Chris M. and Findlay, Scott D. and Oni, Adedapo A. and Chan, Tsung-ta E. and Koch, Carl C. and Jones, Jacob L. and Allen, Leslie J. and et al.}, year={2015}, month={Aug}, pages={946–952} }
 @article{jones_lebeau_nikkel_oni_dycus_cozzan_lin_chernatynskiy_nino_sinnott_et al._2015, title={Combined experimental and computational methods reveal the evolution of buried interfaces during synthesis of ferroelectric thin films}, volume={2}, number={10}, journal={Advanced Materials Interfaces}, author={Jones, J. L. and LeBeau, J. M. and Nikkel, J. and Oni, A. A. and Dycus, J. H. and Cozzan, C. and Lin, F. Y. and Chernatynskiy, A. and Nino, J. C. and Sinnott, S. B. and et al.}, year={2015} }
 @article{dycus_white_pierce_venkatasubramanian_lebeau_2013, title={Atomic scale structure and chemistry of Bi2Te3/GaAs interfaces grown by metallorganic van der Waals epitaxy}, volume={102}, ISSN={["0003-6951"]}, DOI={10.1063/1.4793518}, abstractNote={Here, we report the atomic scale structure and chemistry of epitaxial Bi2Te3 thin films grown via metallorganic chemical vapor deposition on (001) GaAs substrates. Using aberration corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF STEM), we report an atomically abrupt interface spanned by a second phase. Further, we demonstrate that interpretation of HAADF STEM image intensities does not provide an unambiguous interface structure. Combining atomic resolution imaging and spectroscopy, we determine the identity of the interfacial species is found to be consistent with that of a bilayer of Ga–Te that terminates GaAs dangling bonds.}, number={8}, journal={APPLIED PHYSICS LETTERS}, author={Dycus, J. Houston and White, Ryan M. and Pierce, Jonathan M. and Venkatasubramanian, Rama and LeBeau, James M.}, year={2013}, month={Feb} }