A5068141356- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- Semiconductor Quantum Structures and Devices
- Surface and Thin Film Phenomena
- Advanced Physical and Chemical Molecular Interactions
- Magnetic properties of thin films
- Topological Materials and Phenomena
- ZnO doping and properties
- Graphene research and applications
- Semiconductor materials and devices
- Advanced Chemical Physics Studies
- Electron and X-Ray Spectroscopy Techniques
- Advancements in Semiconductor Devices and Circuit Design
- Semiconductor materials and interfaces
- GaN-based semiconductor devices and materials
- History and advancements in chemistry
- Magnetic and transport properties of perovskites and related materials
- Gas Sensing Nanomaterials and Sensors
- Transition Metal Oxide Nanomaterials
- Quantum, superfluid, helium dynamics
- Quantum Information and Cryptography
- Molecular Junctions and Nanostructures
- Spectral Theory in Mathematical Physics
- Cold Atom Physics and Bose-Einstein Condensates
- Electronic and Structural Properties of Oxides
Pusan National University
2005-2018
University of Ulsan
2016
Pohang University of Science and Technology
2009
University of Tennessee at Knoxville
1996-2005
South College
2001
Arizona State University
1984-1992
Brown University
1980-1983
Colorado State University
1983
Korea University
1978
Quantum confinement of carriers has a substantial impact on nanoscale device operations. We present electrical transport analysis for lithographically fabricated sub-5 nm thick Si nanowire field-effect transistors and show that confinement-induced quantum oscillations prevail at 300 K. Our results discern the basis recent observations performance enhancement in ultrathin provide direct experimental evidence theoretical predictions enhanced carrier mobility strongly confined devices.
An ambipolar dual-channel field-effect transistor (FET) with a WSe2 /MoS2 heterostructure formed by separately controlled individual channel layers is demonstrated. The FET shows switchable behavior independent carrier transport of electrons and holes in the MoS2 , respectively. Moreover, photoresponse studied at heterointerface FET.
The energy spectra and wavefunctions of up to 14 interacting quasielectrons (QE's) in the Laughlin nu=1/3 fractional quantum Hall (FQH) state are investigated using exact numerical diagonalization. It is shown that at sufficiently high density QE's form pairs or larger clusters. This behavior, opposite correlations, invalidates (sometimes invoked) reapplication composite fermion picture individual QE's. series finite-size incompressible ground states identified QE filling factors nu_QE=1/2,...
We studied insulator–metal transitions in VO2 nanobeams for both abrupt and gradual changes applied electric fields. Based on the observations, Poole–Frenkel effect explained transition, while case is found to be dominated by Joule heating phenomenon. also carried out power model finite element method based simulations which supported phenomena transition. An in-principle demonstration of effect, performed using a square voltage pulse 1 µs duration, further confirms proposed transition...
Numerical results for the energy spectra of $N$ electrons on a spherical surface are used as input data to determine quasiparticle energies and pairwise ``Fermi liquid'' interactions composite Fermion (CF) excitations in fractional quantum Hall systems. The their then spectra, $E$ vs total angular momentum $L$, states containing more than two quasiparticles. qualitative agreement with numerical gives remarkable new confirmation CF picture.
A composite fermion hierarchy theory is constructed in a way related to the original Haldane picture by applying (CF) transformation quasiparticles of Jain states. It shown that coincides with for principal CF fillings. Within Fermi liquid approach few-electron systems on sphere, simple interpretation many-quasiparticle spectra given, and provides an explanation failure when applied hierarchical $4/11$ state.
The electronic properties of surface space-charge layers on semiconductors whose constant-energy surfaces are ellipsoids arbitrarily oriented with respect to the investigated. Optical absorption and its relation collective modes system examined within a framework energy-functional perturbation theory. Linear-response theory quasi-two-dimensional is applied study polarization dependence intersubband spectra for Si(111) Si(110) inverstion layers. Both normal (six- or fourfold) valley occupancy...
We investigate low-energy electronic states and heat capacity of graphene strips. The density is obtained by diagonalizing a lattice Hamiltonian for strips with zigzag armchair edges, respectively. modes localized at strip edges in geometry reveal peculiar near the zero-energy line. find that overall behavior ${C}_{\mathrm{el}}(T)$ similar to two-level system, low-temperature shows unconventional ${C}_{\mathrm{el}}\ensuremath{\propto}{T}^{\ensuremath{\alpha}}$...
The material properties of semiconductor nanowires are greatly affected by electrical, optical, and chemical processes occurring at their surfaces because the very large surface-to-volume ratio. Precise control over doping as well surface charge has been demonstrated in thin films for fundamental physics application-oriented research. However, behavior is expected to differ markedly from bulk conventional materials. Here, we show that placing gold nanoparticles, controlled manner, on an...
Electron-hole systems on a Haldane sphere are studied by exact numerical diagonalization. Low-lying states contain one or more types of bound charged excitonic complexes ${X}_{k}^{\ensuremath{-}},$ interacting through appropriate pseudopotentials. Incompressible ground such multicomponent plasmas found. A generalized Laughlin wave function and composite fermion picture shown to predict the low-lying an electron-hole gas at any value magnetic field.
We present a self-consistent calculation of magnetic phase structure in modulation-doped dilute III-V semiconductor quantum wells. The spin-split subband is calculated at finite temperature and magnetic-field effects on the carrier-induced magnetism are examined weak-field regime. exchange correlation free carriers shown to enhance ferromagnetic tendency. And ${T}_{\mathrm{th}},$ below which system spontaneously becomes fully spin polarized, increases as doping concentration ${N}_{a}$...
The electronic properties of spin-symmetry-broken dilute magnetic semiconductor quantum wells are investigated self-consistently at zero temperature. spin-split subband structure and carrier concentration modulation-doped examined in the presence a strong field. effects exchange correlations electrons included local-spin--density-functional approximation. We demonstrate that correlation decreases energy but enhances density spin-polarized well. also observe as field increases, spin-down...
The quantum entanglement of the ground state and thermal mixed a three-qubit system with Heisenberg interaction are investigated in detail presence an inhomogeneous magnetic field. concurrence model is compared magnetization, threshold temperature discussed. effects field coupling coefficient also examined by considering two-qubit systems. We found that exists at temperatures below even if unentangled.
The relevant correlation functions for the differential mobility and diffusion coefficient are developed here far-from-equilibrium steady state appropriate to high-field transport in semiconductors. We present a unified analysis evolution of several generic related this state. emphasize initial values temporal these functions.
A general linear-response theory is formulated for the quasi-two-dimensional system associated with a surface space-charge layer in semiconductor whose ellipsoidal energy surfaces are arbitrarily oriented relative to surface. The response of self-consistent electromagnetic disturbance described terms microscopic conductivity tensor. gauge invariance established explicitly. effect collision electrons impurities or lattice imperfections accounted by introducing relaxation term into equation...
Here, we investigate the stoichiometry control of GaAs/Al0.3Ga0.7As droplet epitaxy (DE) quantum dots (QDs). Few tens core nonstoichiometries in Ga(As) atomic percent are revealed as-grown "strain-free" QDs using state-of-the-art atomic-scale energy-dispersive X-ray spectroscopy based on transmission electron microscopy. Precise systematic analyses demonstrate a successful quenching nonstoichiometry below 2%. The chemical reactions with well-controlled ex situ annealing sheds light...
The charge and spin response of a spin-polarized electron gas is investigated including terms beyond the random-phase approximation. We evaluate response, longitudinal transverse mixed spin-charge self-consistently in susceptibility functions noninteracting system. Exchange-correlation effects between electrons \ensuremath{\sigma} \ensuremath{\sigma}\ensuremath{'} are included following Kukkonen Overhauser, by using spin-polarization-dependent generalized Hubbard local-field factors...