A5082947713- Quantum Dots Synthesis And Properties
- Nanocluster Synthesis and Applications
- Chalcogenide Semiconductor Thin Films
- Electronic and Structural Properties of Oxides
- Advanced Electron Microscopy Techniques and Applications
- Gold and Silver Nanoparticles Synthesis and Applications
- Silicon Nanostructures and Photoluminescence
- Magnetic properties of thin films
- Semiconductor materials and devices
- Quantum and electron transport phenomena
- Topological Materials and Phenomena
- Graphene research and applications
- Magnetic and transport properties of perovskites and related materials
- Advanced Materials Characterization Techniques
- Ion-surface interactions and analysis
- Copper-based nanomaterials and applications
- Catalysis and Hydrodesulfurization Studies
- Force Microscopy Techniques and Applications
- Ga2O3 and related materials
- 2D Materials and Applications
- Electron and X-Ray Spectroscopy Techniques
- Thermal Radiation and Cooling Technologies
- Thermal properties of materials
- Advanced Thermoelectric Materials and Devices
- Diamond and Carbon-based Materials Research
University of Minnesota
2015-2023
ETH Zurich
2021-2023
University of Missouri
2020
Twin Cities Orthopedics
2020
Pennsylvania State University
2014
MRC Laboratory of Molecular Biology
1978
Massachusetts Institute of Technology
1978
University of Wisconsin–Madison
1978
Structural, magnetic, and transport studies have been performed on perpendicular magnetic tunnel junctions (pMTJ) with Mo as the buffer capping layers. After annealing samples at 300 °C higher, consistently better performance was obtained compared to that of conventional pMTJs Ta Large tunneling magnetoresistance (TMR) anisotropy (PMA) values were retained in a wide range layers after for 2 h 400 °C, sharp contrast layers, which superparamagnetic behavior nearly vanishing observed. As result...
Metal oxide semiconductor nanocrystals (NCs) exhibit localized surface plasmon resonances (LSPRs) tunable within the infrared (IR) region of electromagnetic spectrum by vacancy or impurity doping. Although a variety these NCs have been produced using colloidal synthesis methods, incorporation and activation dopants in liquid phase has often challenging. Herein, Al-doped ZnO (AZO) as an example, we demonstrate potential nonthermal plasma alternative strategy for production doped metal NCs....
Titanium nitride has attracted attention for its plasmonic properties as a thermally stable, biocompatible, and cost-effective alternative to gold. In this work, we synthesized titanium nanocrystals in nonthermal plasma using tetrakis (dimethylamino) (TDMAT) ammonia the nitrogen precursors. Extinction measurements of as-produced 6–8 nm exhibit broad plasmon resonance peaking near 800 nm, possibly suitable photothermal therapy treatments. Ammonia flow rate power were found affect nanocrystal...
Silicon quantum dots (Si QDs) are attractive, nontoxic luminophores for luminescent solar concentrators (LSCs). Here, we produced Si QD/poly(methyl methacrylate) (PMMA) films on glass by doctor-blading polymer solutions and achieved with low light scattering at an order of magnitude higher QD weight fraction than has been previously in the bulk. We suggest that fast solidification rate as compared to slow bulk polymerization is enabling factor avoiding large agglomerates within...
In this work, we present an all-gas-phase approach for the synthesis of quantum-confined core/shell nanocrystals (NCs) as a promising alternative to traditional solution-based methods. Spherical quantum dots (QDs) are grown using single-stage flow-through nonthermal plasma, yielding monodisperse NCs, with concentric structure confirmed by electron microscopy. The in-flight negative charging NCs plasma electrons keeps NC cores separated during shell growth. success gas-phase is demonstrated...
We studied the spin-to-charge and charge-to-spin conversion at room temperature in sputtered WTe2−x (x = 0.8) (t)/Co20Fe60B20(6 nm) heterostructures. Spin pumping measurements were used to characterize efficiency, spin efficiency was calculated be larger than ∼0.035. Second harmonic Hall carried out estimate ratio. found that system exhibits a large field-like torque (spin ∼0.1) small damping-like ∼0.001) compared those reported for heavy metals. High-resolution transmission electron...
We report spin-to-charge and charge-to-spin conversion at room temperature in heterostructure devices that interface an archetypal Dirac semimetal, Cd3As2, with a metallic ferromagnet, Ni0.80Fe0.20 (permalloy). The spin-charge interconversion is detected by both spin torque ferromagnetic resonance driven pumping. Analysis of the symmetric anti-symmetric components mixing voltage frequency power dependence pumping signal show behavior these processes consistent previously reported mechanisms...
Magic-sized semiconductor nanocrystals (MSNCs) grow via discrete jumps between specific sizes. Despite their potential to offer atomically precise structures, use has been limited by poor stability and trap-dominated photoluminescence. Recently, CdSe MSNCs have grown larger We exploit such particles demonstrate a method shells on MSNC cores high-temperature synthesis. Thin CdS lead dramatic improvements in the emissive properties of MSNCs, narrowing fluorescence line widths, enhancing...
Many envisioned applications of semiconductor nanocrystals (NCs), such as thermoelectric generators and transparent conductors, require metallic (nonactivated) charge transport across an NC network. Although encouraging signs or near-metallic have been reported, a thorough demonstration nonzero conductivity, σ, in the 0 K limit has elusive. Here, we examine temperature dependence σ ZnO networks. Attaining both higher lower than previous studies NCs (T low 50 mK), observe clear transition...
Through a combination of thin film growth, hard X-ray photoelectron spectroscopy (HAXPES), scanning transmission electron microscopy/electron energy loss (STEM/EELS), magneto-transport measurements, and transport modeling, we report on the demonstration modulation-doping BaSnO3 (BSO) using wider bandgap La-doped SrSnO3 (LSSO) layer. Hard (HAXPES) revealed valence band offset 0.71 +/- 0.02 eV between LSSO BSO resulting in favorable conduction for remote doping LSSO. Nonlinear Hall effect...
Characterization efforts of core/shell and core/multishell nanocrystals have struggled to quantitatively evaluate the interface width between core shell materials despite its importance in their optoelectronic properties. Here, we demonstrate a scanning transmission electron microscopy (STEM) method for measuring radial elemental composition two spherical nanocrystal systems, Ge/Si CdSe/CdS/ZnS core/double-shell nanocrystals. By fitting model-based distributions elements measured...
Molybdenum disulfide (MoS
Strain-free ${\mathrm{Fe}}_{16}{\mathrm{N}}_{2}$ thin films were obtained on MgO (001) single-crystal substrates with Cr seed layers. X-ray diffraction and transmission electron microscopy confirmed that the film is textured in all three spatial directions crystallographic orientation determined by epitaxial constraints from substrate. Average grain size was estimated to be range of tens nanometers. Ten pieces 40-nm-thick thin-film samples stacked together for half-polarized neutron study at...
Silicon-germanium is an important thermoelectric material for high temperature applications. In this study, thin films composed of SiGe nanoparticles were synthesized in a plasma reactor and sintered by millisecond pulse width, quasi continuous wave, near infrared laser wavelength 1070 nm. We demonstrate that have electrical low thermal conductivity, dependent on the surface morphology dopant concentration. Substrate wetting heating induced molten was found to play role final films....
Magnetic doping of topological quantum materials provides an attractive route for studying the effects time-reversal symmetry breaking. Thus motivated, we explore introduction transition metal Mn into thin films Dirac semimetal Cd3As2 during growth by molecular beam epitaxy. Scanning transmission electron microscopy measurements show formation a Mn-rich phase at top surface Mn-doped grown using both uniform and delta doping. This suggests that acts as surfactant epitaxial Cd3As2, resulting...
"Magic-sized" nanocrystals (MSNCs) grow in discrete jumps between a series of specific sizes. Consequently, MSNCs have been explored as an alternative route to uniform semiconductor particles, potentially with atomic precision. However, because the growth mechanism has poorly understood, best strategies control MSNC syntheses and obtain desired sizes are unknown. Experiments found that common parameters, such time temperature, limited utility. Here, we theoretically experimentally...
Quantitatively calibrated annular dark field scanning transmission electron microscopy (ADF-STEM) imaging experiments were compared to frozen phonon multislice simulations adapted include chemical bonding effects. Having carefully matched simulation parameters experimental conditions, a depth-dependent effect was observed for high-angle ADF-STEM of aluminum nitride. This result is explained by computational predictions, systematically examined in the preceding portion this study, showing...
Gamma alumina (γ-Al
Semiconductor materials with independently controlled electrical and thermal properties have a unique promise for energy-related applications from thermoelectrics thermophotovoltaics. Here, using nonthermal plasma synthesized, direct-contact zinc oxide (ZnO) nanocrystal (NC) networks infilled amorphous $\mathrm{A}{\mathrm{l}}_{2}{\mathrm{O}}_{3}$, ZnO-$\mathrm{A}{\mathrm{l}}_{2}{\mathrm{O}}_{3}$ mixture, it is shown that such independent control of achievable. In this study, in addition to...
The authors produce plasmonic ZnO-TiN nanocomposite films by depositing plasma-synthesized ZnO nanocrystals onto a substrate and then infilling the nanocrystal network's pores with TiN via remote plasma-enhanced atomic layer deposition (PEALD). This exhibits resonance that is blueshifted compared to planar titanium nitride thin films. study effects of PEALD conditions film thickness on response these nanocomposites exploit optimized in device generates photocurrent at zero bias.