Kibog Park

We introduce a new type of multi-functional capacitive sensor that can sense several different external stimuli. It is fabricated only with polydimethylsiloxane (PDMS) films and silver nanowire electrodes by using selective oxygen plasma treatment method without photolithography and etching processes. Differently from the conventional single-capacitor multi-functional sensors, our new multi-functional sensor is composed of two vertically-stacked capacitors (dual-capacitor). The unique dual-capac

We report the systematic experimental studies demonstrating that a graphene layer inserted at metal/n-Si(001) interface is efficient to explore interface Fermi-level pinning effect. It is confirmed that an inserted graphene layer prevents atomic interdiffusion to form an atomically abrupt Schottky contact. The Schottky barriers of metal/graphene/n-Si(001) junctions show a very weak dependence on metal work-function, implying that the metal Fermi-level is almost completely pinned at charge neutra

We show that “single” stacking fault 3C inclusions formed in 4H-SiC p-i-n diodes behave as electron quantum wells (QWs) with the QW energy depth of ∼0.25eV below 4H-SiC conduction band minimum, by measuring the Schottky barriers on and away from inclusions with ballistic electron emission microscopy (BEEM). The Schottky barrier on the 4H area ([11-20] oriented) is measured to be essentially the same as (0001) plane studied previously, indicating that the interface pinning effects on both crystal

It is demonstrated that the electric dipole layer due to the overlapping of electron wave functions at the metal/graphene contact results in a negative Fermi-level pinning effect on the region of the GaAs surface with low interface-trap density in the metal/graphene/n-GaAs(001) junction. The graphene interlayer plays the role of a diffusion barrier, preventing the atomic intermixing at the interface and preserving the low interface-trap density region. The negative Fermi-level pinning effect is

Finite-element calculations of Schottky diode capacitance-voltage (C-V) curves show that an array of subsurface inclined quantum wells (QWs) produce negligible change in shape and slope of C-V curves, but significantly reduce the intercept voltage. This is particularly important for hexagonal SiC, in which current- or process-induced cubic inclusions are known to behave as electron QWs. These calculations naturally explain the surprisingly large effect of cubic inclusions on the apparent 4H–SiC

p -type Schottky barriers in Pt∕3C-SiC contacts have been measured using ballistic hole emission microscopy (BHEM) and estimated to be ∼0.06eV higher than identically prepared Pt∕p-type 4H-SiC contacts. This indicates the 3C-SiC valence band maximum (VBM) is ∼0.06eV below the 4H-SiC VBM, consistent with the calculated ∼0.05eV type-II valence band offset between these polytypes. We also observe no evidence of an additional VBM in 3C-SiC, which supports the proposal that the second VBM observed in

Abstract A new concept of read-out method for ferroelectric random-access memory (FeRAM) using a graphene layer as the channel material of bottom-gated field effect transistor structure is demonstrated experimentally. The transconductance of the graphene channel is found to change its sign depending on the direction of spontaneous polarization (SP) in the underlying ferroelectric layer. This indicates that the memory state of FeRAM, specified by the SP direction of the ferroelectric layer, can b

Terahertz (THz) detectors have been extensively studied for various applications such as security, wireless communication, and medical imaging. In case of metal-insulator-metal (MIM) tunnel junction THz detector, a small junction area is desirable because the detector response time can be shortened by reducing it. An edge metal-semiconductor-metal (EMSM) junction has been developed with a small junction area controlled precisely by the thicknesses of metal and semiconductor films. The voltage re

An enormous amount of research activities has been devoted to developing new types of non-volatile memory devices as the potential replacements of current flash memory devices. Theoretical device modeling was performed to demonstrate that a huge change of tunnel resistance in an Edge Metal-Insulator-Metal (EMIM) junction of metal crossbar structure can be induced by the modulation of electric fringe field, associated with the polarization reversal of an underlying ferroelectric layer. It is demo

It is demonstrated that the heart-rate can be sensed capacitively on a touch screen panel (TSP) together with touch signals. The existing heart-rate sensing systems measure blood pulses by tracing the amount of light reflected from blood vessels during a number of cardiac cycles. This type of sensing system requires a considerable amount of power and space to be implemented in multi-functional mobile devices such as smart phones. It is found that the variation of the effective dielectric constan

Ballistic electron emission microscopy was used to measure the increase of local Schottky barrier (compared to the surrounding 4H-SiC area) over a partial 8H-SiC layer that is the surface-exposed tail of an 8H stacking fault inclusion extending from 4H substrate. This local increase is believed to be due to polarization charge induced at the interface of partial 8H layer and underlying 4H host, resulting from the spontaneous polarization (SP) difference between SiC regions with different bilayer

Ⅲ. 연구개발의 내용 및 범위 ○ Hexagonal SiC (4H, 6H) 기판 상에 전자빔을 조사하여 표면 근처에서 발생하는 결정구조 변화 양상을 파악하고 이의 금속/SiC 접합면의 전기적 특성 변화와의 연관성을 규명함. ○ 전자빔 조사를 통한 표면 국한 가열을 통해 그래핀 에피막을 형성할 수 있는 실험적 조건을 탐색하고 형성된 그래핀 에피막의 구조적, 전기적 특성을 분석함.

Abstract The effective work‐function of metal electrode is one of the major factors to determine the threshold voltage of metal/oxide/semiconductor junction. In this work, it is demonstrated experimentally that the effective work‐function of the Aluminum (Al) electrode in Al/SiO 2 /n‐Si junction increases significantly by ≈1.04 eV with the graphene interlayer inserted at Al/SiO 2 interface. The device‐physical analysis of solving Poisson equation analytically is provided when the flat‐band volta