Mann–Ho Cho

We performed plasma doping of nitrogen into single-layer graphene on SiO2. Using aluminum oxide as a buffer layer to reduce the plasma damage, up to 19.7% nitrogen was substitutionally doped into graphene. The nitrogen doping of graphene was confirmed by Raman and X-ray photoemission spectroscopy analyses. The n-doping property of the N-doped graphene was measured by Raman spectroscopy. Raman mapping was carried out to statistically confirm the Dirac cone shift of graphene resulting from the N-d

This study used a spatially controlled boron-doping technique that enables a p-n junction diode to be realized within a single 2D black phosphorus (BP) nanosheet for high-performance photovoltaic application. The reliability of the BP surface and state-of-the-art 2D p-n heterostructure's gated junctions was obtained using the controllable pulsed-plasma process technique. Chemical and structural analyses of the boron-doped BP were performed using X-ray photoelectron spectroscopy, transmission ele

Although Sb₂Te₃, as a candidate material for next-generation memory devices, has attractive properties such as higher operation speed and lower power consumption than Ge₂Sb₂Te₅, its poor stability prevents its application to commercial memory devices. Transition metal dopants provide enhancements in its phase change characteristics, improving both thermal stability and operation energy. However, the enhancement mechanism remains to be suffic

In a three-dimensional topological insulator Bi2Se3, a stress control for band gap manipulation was predicted but no systematic investigation has been performed yet due to the requirement of large external stress. We report herein on the strain-dependent results for Bi2Se3 films of various thicknesses that are grown via a self-organized ordering process. Using small angle X-ray scattering and Raman spectroscopy, the changes of d-spacings in the crystal structure and phonon vibration shifts resul

BN-incorporated amorphous Ge₂Sb₂Te₅ (GST) films were deposited by an ion beam sputtering deposition method. The power-time-effect (PTE) diagrams showed that as the amount of BN increased, the crystallization temperature and phase change speed increased.

Ag-Incorporated Ge₂Sb₂Te₅ (AGST) crystallizes faster and at a lower temperature than Ge₂Sb₂Te₅ (GST) owing to the changes in local structure and chemical bonding.

Topological insulator (TI), a band insulator with topologically protected edge states, is one of the most interesting materials in the field of condensed matter. Bismuth selenide (Bi₂Se₃) is the most spotlighted three-dimensional TI material; it has a Dirac cone at each top and bottom surface and a relatively wide bandgap. For application, suppression of the bulk effect is crucial, but in ultrathin TI materials, with thicknesses less than 3 QL, the finite size effect works

Owing to their remarkable spin-charge conversion (SCC) efficiency, topological insulators (TIs) are the most attractive candidates for spin-orbit torque generators. The simple method of enhancing SCC efficiency is to reduce the thickness of TI films to minimize the trivial bulk contribution. However, when the thickness reaches the ultrathin regime, the SCC efficiency decreases owing to intersurface hybridization. To overcome these contrary effects, we induced dehybridization of the ultrathin TI

2D multiferroics with combined ferroic orders have gained attention owing to their novel functionality and underlying science. Intrinsic ferroelastic-ferroelectric multiferroicity in single-crystalline van der Waals rhenium dichalcogenides, whose symmetries are broken by the Peierls distortion and layer-stacking order, is demonstrated. Ferroelastic switching of the domain orientation and accompanying anisotropic properties is achieved with 1% uniaxial strain using the polymer encapsulation metho

Topological insulators (TIs) have become popular in the field of optoelectronic devices because of their broadband and high-sensitivity properties, which are attributed to the narrow band gap of the bulk state and high mobility of the Dirac surface state. Although perfectly grown TIs are known to exhibit strong stability against oxidation, in most cases, the existence of vacancy defects in TIs reacts to air and the characteristics of TIs is affected by oxidation. Therefore, changes in the band s

The field-enhanced effect due to the oxygen vacancy distribution improves the memory performance in the TiO₂-based RRAM device.

The thermal stabilities and interfacial properties of HfO2 films created on conditioned i-InP surfaces using atomic layer deposition were investigated. When HfO2 was deposited on sulfur passivation InP substrate, improved interfacial properties and electrical properties were observed by suppressing the interfacial oxides and In or P dangling bonds between HfO2 and InP. X-ray photoelectron spectroscopy (XPS) and thermodynamic data indicated that the acetone–methanol–Isopropanol (AMI) pre-clean pr