A5102005983- Plasma Diagnostics and Applications
- Magnetic confinement fusion research
- Fusion materials and technologies
- Magnetic properties of thin films
- Quantum and electron transport phenomena
- Diamond and Carbon-based Materials Research
- Metal and Thin Film Mechanics
- ZnO doping and properties
- Physics of Superconductivity and Magnetism
- Ga2O3 and related materials
- Magnetic Properties and Applications
- Laser-induced spectroscopy and plasma
- Copper-based nanomaterials and applications
- Magnetic Properties of Alloys
- Tunneling and Rock Mechanics
- Semiconductor materials and devices
- Electromagnetic Launch and Propulsion Technology
- Geotechnical Engineering and Analysis
- Structural Health Monitoring Techniques
- Non-Destructive Testing Techniques
- Fusion and Plasma Physics Studies
- Ion-surface interactions and analysis
- Marine Biology and Environmental Chemistry
- Muon and positron interactions and applications
- Energetic Materials and Combustion
University of Illinois Urbana-Champaign
2002-2017
Seoul National University
2008-2011
Pohang University of Science and Technology
2002-2006
We report metalorganic vapor-phase epitaxial growth and structural photoluminescent characteristics of ZnO nanorods. The nanorods were grown on Al2O3(00⋅1) substrates at 400 °C without employing any metal catalysts usually needed in other methods. Electron microscopy revealed that with uniform distributions their diameters, lengths, densities vertically from the substrates. mean diameter is as narrow 25 nm. In addition, x-ray diffraction measurements clearly show epitaxially homogeneous...
We report on the photoluminescent characteristics of ZnO single crystal nanorods grown by catalyst-free metalorganic vapor phase epitaxy. From photoluminescence (PL) spectra at 10 K, several PL peaks were observed 3.376, 3.364, 3.360, and 3.359 eV. The peak 3.376 eV is attributed to a free exciton while other are ascribed neutral donor bound peaks. observation K indicates that prepared method high optical quality.
Abstract Neural network (NN) based constitutive models can capture non‐linear material behaviour. These are versatile and have the capacity to continuously learn as additional response data becomes available. NN increasingly used within finite element (FE) method for solution of boundary value problems. models, unlike commonly plasticity do not require special integration procedures implementation in FE analysis. model formulation does use a stiffness matrix concept contrast elasto‐plastic...
We report on photoluminescence (PL) spectra of ZnO films grown by low pressure metalorganic vapor phase epitaxy. For PL measurements, high quality thin were epitaxially Al2O3(0001) substrates. Time-integrated the at 10 K clearly exhibited free A and B excitons 3.376 3.382 eV bound exciton peaks 3.360, 3.364, 3.367 eV. With increasing temperature, intensities drastically decreased a peak was dominant above 40 K. Furthermore, time-resolved measurements carried out room temperature. The decay...
Modulated pulse power (MPP) technology is a derivative of high pulsed magnetron sputtering that allows unprecedented user control over the growth process, although critical time-dependent plasma properties during have not been studied until now. Using MPP generator, pulses custom voltage waveforms were generated and applied to cathode 36 cm diameter circular planar magnetron. The I-V characteristics are separable into distinct discharge stages. A time-resolved triple Langmuir probe was...
The spin transfer torque generated by a spin-polarized current can induce the shift of magnetic domain-wall position. In this work, we study theoretically current-induced motion using collective coordinate approach [Gen Tatara and Hiroshi Kohno, Phys. Rev. Lett. 92, 86601 (2004)]. is extended to include not only position polarization angle changes but also width variation. It demonstrated that variation affects critical current.
To investigate the effect of lithium on a molybdenum target, triple Langmuir probe diagnostics and target temperature measurements are carried out. Several experimental scenarios tested to optimize device for vapor shielding experiment. A sputtering system is used deposit target. placed near at various pressures estimate change plasma density electron their effects shielding. Temperature increase measured by thermocouple its relationship with parameters discussed in detail.
This article implements a new data-driven inverse analysis method, SelfSim (self-learning simulations), for extracting material behaviour of metals. uses load-displacement measurements from structural tests whereby the experiences non-uniform stresses and strains to extract constitutive in form stress-strain database unconstrained by pre-defined model. The method is verified using simulated physical experiments on metal structures. successfully extracts anisotropic response aluminium...
We demonstrate theoretically that the spin polarization of currents can be electrically amplified within nonmagnetic semiconductors by exploiting fact current, compared to charge is weakly perturbed electric driving forces. As a specific example, we consider $T$-shaped current branching geometry made entirely semiconductor, where injected into one branches (input branch) and splits other two (output branches). show when input has moderate polarization, in output higher than branch may reach...
A self-consistent circuit model which can describe the dynamic behavior of entire pulsed system for plasma source ion implantation has been developed and verified with experiments. In model, one-dimensional fluid equations sheath have numerically solved boundary conditions from external including power system. Experiments conducted by applying negative, high-voltage pulses up to -10 kV a capacitor-based pulse modulator planar target in contact low-pressure argon produced radio-frequency at...
We study the spin injection in ferromagnet-tunnel barrier-semiconductor heterojunction structure embedded current-branching scheme. The current branching enables one to separately control charge from current. As a result, it is possible electrically polarization within semiconductor. Moreover, can be enhanced further and may reach 100% by properly tuning branched currents. Since proposed scheme does not require low temperature operation, useful tool generate high at room temperature. (© 2006...
We show that the injection of a pure spin current (not accompanied by charge current) into ring can induce circulating in ring, provided transport coefficients are dependent and inhomogeneous. As an example, we consider hybrid ferromagnet--normal-metal system calculate magnitude induced injection. This phenomenon may have relevance for spintronic applications.
To investigate an effect of lithium on a molybdenum target, triple Langmuir probe diagnostics [1-3] and target temperature measurement are carried out. Several experimental scenarios tested to optimize the device for vapor shielding experiment. A sputtering system is used deposit target. placed near at various pressures estimate change plasma density electron their effects shielding. Temperature increase measured by thermocouple its relation with parameter discussed in detail.
Summary form only given. High power pulsed magnetron sputtering (HPPMS) and its derivative, modulated pulse (MPP) were studied in a 36 cm diameter circular planar magnetron, using Ti target an Ar atmosphere. The discharge characteristics time-dependent plasma behaviors measured to further understand their individual mechanisms performances. HPPMS generator allowed direct change of the voltage control current arcing events. MPP, on other hand, had advantage flexibly adjusting on- off-time for...