Geunseop Lee

Learn More
The solution of an ill-conditioned total least squares (TLS) problem from highresolution imaging by the regularization approach of Golub, Hansen, and O’Leary [SIAM J. Matrix Anal. Appl., 21 (2000), pp. 185–194] is considered. This work solves the regularized TLS problem as a system of nonlinear equations in the two regularization parameters. Since the(More)
We investigate the initial stage of the C incorporation into Si(001) using thermal dissociation of C2H2. The scanning tunneling microscopy shows that C-induced dimer vacancies (DVs) with depressed adjacent dimers are generated on the surface and aligned in the dimer direction, forming the 2xn structure. The ab initio pseudopotential calculations reveal(More)
We report direct visualizations of the fluctuation and condensation phenomena in a phase transition of a one-dimensional (1D) In/Si(111) system using scanning tunneling microscopy. The high-temperature (HT) and low-temperature (LT) phases are found to coexist on the nanometer scale near Tc. Above Tc, 1D LT-phase stripes fluctuate in the HT phase and(More)
The C amount and the structure of the Si(001)-c(4 x 4) surface is studied using scanning tunneling microscopy (STM) and ab initio calculations. The c(4 x 4) phase is found to contain 1/8 monolayer C (1 C atom in each primitive unit cell). From the C amount and the symmetry of high-resolution STM images, it is inferred that the C atoms substitute the(More)
The structural (4 x 1) to (8 x 2) transition and the electronic metal to semimetal transition at the In/Si interface are studied with scanning tunneling microscopy and spectroscopy. Both transitions are gradual, resulting in a complex domain structure in the transition temperature regime. At these intermediate temperatures, the metallic (4 x 1) and(More)
Semiconductor surfaces and ultrathin interfaces exhibit an interesting variety of two-dimensional quantum matter phases, such as charge density waves, spin density waves and superconducting condensates. Yet, the electronic properties of these broken symmetry phases are extremely difficult to control due to the inherent difficulty of doping a strictly(More)
A simple procedure for the fabrication of sub-10 nm scale Si nanopillars in a 2-D array using reactive ion etching with 8 nm Co nanoparticles as etch masks is demonstrated. The obtained Si nanopillars are single crystalline tapered pillar structures of 5 nm (top) x 8 nm (bottom) with a density of approximately 4 x 10(10) pillars cm(-2) on the substrate,(More)
Using low-energy electron diffraction and scanning tunnelling microscopy, we studied the formation of Mg silicide and metallic Mg islands on a Si(111)-7 × 7 surface at room temperature as a function of Mg coverage. We found that the mechanism by which Mg islands grew on the Si(111)-7 × 7 surface, and the morphology of the islands that formed, depended on(More)
We have investigated the surface atomic structure of boundary area of Li- and Na-induced Ge(111)3 × 1 reconstruction using scanning tunneling microscope. On Li/Ge(111)3 × 1, the 3 × 1 phase was found to be terminated with a single row in the filled-state image and with dimer-like features in the empty-state image. The images of both interior and boundary of(More)
  • 1