Son Jong Yeog

Molecular electronic devices that utilize single molecules or molecular monolayers as active electronic components represent a promising approach in the ongoing miniaturization and integration of electronic devices. Rapid advances in technology have enabled us to engineer molecular electronic devices with diverse functionalities. Significant progress has been made in understanding charge transport in molecular systems at the single-molecule level, and concomitantly, new device concepts have emer

We report the enhanced multiferroic properties of a ytterbium (Yb)- doped BiFeO3 thin film (Bi0.85Yb0.15FeO3) deposited on a (001) SrRuO3/ (100) SrTiO3 substrate by pulsed laser deposition. The crystal structure, surface morphology, ferroelectric domain structure, and the electrical and magnetic behavior of the epitaxial Bi0.85Yb0.15FeO3 film, 100 nm in thickness, were investigated. The results were compared with those of an undoped BiFeO3 thin film. The x-ray diffraction patterns showed that bo

In this paper, the behavior of zinc oxide (ZnO) thin films etched by using a diluted CF_4 plasma was investigated. We controlled the substrate bias power of the inductively coupled-plasma (ICP) etching system and the CF_4/Ar gas ratio to improve the etching rate. We accomplished a high etching rate of 144.85 nm/min at a substrate bias power (Sbp) of 200 W under a low ICP power of 200 W. Chemical bonding evaluated by using X-ray photoemission spectroscopy shows the formation of zinc compounds as

Highly (111)-oriented polycrystalline NaNbO3 (NNO) thin films were deposited on Pt/Ta/glass substrates by pulsed laser deposition. To obtain a well-crystallized Pt bottom electrode on glass substrates, Ta buffer layers were employed between Pt bottom electrodes and glass substrates. The NNO thin film exhibited good ferroelectricity with high remanent polarization (2Pr ≈ 46 μC/cm2) and leakage current density (~2 × 10−6 A/ cm2 at 500 kV/cm). Based on a piezoelectric force microscope study, it is

We report a nanoscale magnetic conducting filament in a resistive random accessmemory (RRAM) device by the direct investigation of conducting nanobits in NiOthin films using magnetic force microscopy. The conducting nanobit in a NiORRAM capacitor formed by CAFM and KFM exhibited a typical bistable resistiveswitching characteristic. The magnetizations of the conducting nanobit weremeasured as a function of the set-reset switching cycle and as the switching cycleswere increased, a strong ferromagn

We investigated ferroelectric characteristics of BiFeO3 (BFO) thin films on SrRuO3 (SRO)/yttria-stabilized zirconia (YSZ)/glass substrates grown by pulsed laser deposition. YSZ buffer layers were employed to grow highly crystallized BFO thin films as well as SRO bottom electrodes on glass substrates. The BFO thin films exhibited good ferroelectric properties with a remanent polarization of 2Pr = 59.6 μC/cm2 and fast switching behavior within about 125 ns. Piezoelectric force microscopy (PFM) stu

La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM) and La0.8Sr0.2Ga0.8Mg0.115Co0.085O3 (LSGMC) thin films were deposited on single crystalline (001) Al2O3 substrates using a pulsed laser deposition technique. The LSGM and LSGMC thin films exhibited only a single phase, which was verified through x-ray diffraction (XRD) experiments. Scanning electron microscopy (SEM) showed that the grain size of the LSGM film was smaller than that of the LSGMC films. Below 800 K, the ionic conductivity of both the thin films was hig

We fabricated high quality epitaxial Bi0.9Ho0.1FeO3 thin films which exhibited the tetragonally stained structure with a c/a ratio of about 1.04. The Bi0.9Ho0.1FeO3 thin film showed a good ferroelectric property with the high remanent polarization (Pr) of about 80 mC/cm2. The ferromagnetic hysteresis loop with a clear remanent magnetization was shown. The coercive field and the remanent magnetization of the Bi0.9Ho0.1FeO3 film are 6200 Oe and 1.7 emu/g, respectively. The abrupt conduction due to

10 nm보다 작은 PbTiO_3 (PTO) 나노점들의 강유전 특성을연구하였다. 딥팬 리소그래피 (dip pen lithography)로 40 nm PTO 나노점을 제작하고, 원자 힘 현미경 팁 (atomic force microscopy tip,AFM tip)을 이용하여 이 나노점의 분쇄 공정을 실행하였다. 압전력현미경 (piezoresponse force microscope, PFM)을 이용하여 분쇄된나노점들의 강유전 스위칭 실험을 실시하였다. 10 nm보다 작은 PTO 나노점은 두 강유전 분극들에 의존하는 두 전류들의 차이가 명확하게나타나며, 우수한 강유전 특성을 나타내었다.

Polycrystalline YCrO3 thin films were deposited on (111) Pt/Ta/glasssubstrates by pulsed laser deposition. The YCrO3 thin films exhibited goodferroelectric properties with remnant polarization of about 5 μC/cm2. Largeleakage current was observed by I-V curve and ferroelectric hysteresis loop. The YCrO3 resistive random access memory (RRAM) capacitor showedunipolar switching behaviors with SET and RESET voltages higher thanthose of general NiO RRAM capacitors.

Significant progress has been made in the enhancement of multiferroic properties with possibilities for energy harvesting and storage applications. In this study, BiFeO3 (BFO) thin films were doped with Ca, and the multiferroic, piezoelectric, and energy-storage properties of Bi1−xCaxFeO3−δ (x = 0.3, BCFO) thin films were compared with those of BFO to investigate the effects of the doping. The BCFO thin films were deposited on Pt/TiO2/SiO2/Si substrates using pulsed laser deposition. The BCFO th

We investigated the crystallinity, ferroelectric properties, and energy storage effi ciency of Aurivillius BaBi 4Ti4O15 (BBTO) thin fi lms epitaxially deposited on single-crystal (001) Rh substrates by pulsed laser deposition method. From X-ray dif- fraction experiments, it was confi rmed that the BBTO thin fi lms had a mixed crystallinity of a-oriented crystallinity and c-oriented crystallinity. The BBTO thin fi lms fabricated by a low substrate temperature and a high deposition rate showed highly a-