• Title, Summary, Keyword: Active layer

Search Result 1,269, Processing Time 0.041 seconds

The Characteristics of Amorphous-Oxide-Semiconductor Thin-Film-Transistors According to the Active-Layer Structure (능동층 구조에 따른 비정질산화물반도체 박막트랜지스터의 특성)

  • Lee, Ho-Nyeon
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.10 no.7
    • /
    • pp.1489-1496
    • /
    • 2009
  • Amorphous indium-gallium-zinc-oxide thin-film-transistors (TFTs) were modeled successfully. Dependence of TFT characteristics on structure, thickness, and equilibrium electron-density of the active layer was studied. For mono-active-layer TFTs, a thinner active layer had higher field-effect mobility. Threshold voltage showed the smallest absolute value for the 20 nm active-layer. Subthreshold swing showed almost no dependence on active-layer thickness. For the double-active-layer case, better switching performances were obtained for TFTs with bottom active layers with higher equilibrium electron density. TFTs with thinner active layers had higher mobility. Threshold voltage shifted in the minus direction as a function of the increase in the thickness of the layer with higher equilibrium electron-density. Subthreshold swing showed almost no dependence on active-layer structure. These data will be useful in optimizing the structure, the thickness, and the doping ratio of the active layers of oxide-semiconductor TFTs.

Solution-based Multistacked Active Layer IGZO TFTs

  • Kim, Hyunki;Choi, Byoungdeog
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • /
    • pp.351.1-351.1
    • /
    • 2014
  • In this study, we prepared the solution-based In-Ga-Zn oxide thin film transistors (IGZO TFTs) of multistacked active layer and characterized the gate bias instability by measuring the change in threshold voltage caused by stacking. The solutions for IGZO active layer were prepared by In:Zn=1:1 mole ratio and the ratio of Ga was changed from 20% to 30%. The TFTs with multistacked active layer was fabricated by stacking single, double and triple layers from the prepared solutions. As the number of active layer increases, the saturation mobility shows the value of 1.2, 0.8 and 0.6 (). The electrical properties have the tendency such as decreasing. However when gate bias VG=10 V is forced to gate electrode for 3000 s, the threshold voltage shift was decreased from 4.74 V to 1.27 V. Because the interface is formed between the each layers and this affected the current path to reduce the electrical performances. But the uniformity of active layer was improved by stacking active layer with filling the hole formed during pre-baking so the stability of device was improved. These results suggest that the deposition of multistacked active layer improve the stability of the device.

  • PDF

Vibration Control of Laminated Composite Beams Using Active Constrained Layer Damping Treatment (능동구속감쇠 기법을 이용한 복합적층보의 진동 제어)

  • 강영규;최승복
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.11 no.7
    • /
    • pp.261-266
    • /
    • 2001
  • The flexural vibration of laminated composite beams with active and passive constrained layer damping has been investigated to design a structure with maximum possible damping capacity. The equations of motion are derived fro flexural vibrations of symmetrical,. multi-layer laminated beams. The damping ratio and model damping of the first bending mode are calculated by means of iterative complex eigensolution method. The direct negative velocity feedback control is used for the active constrained layer damping. It is shown that the flexible laminated beam is more effective in the vibration control for both active and passive constrained layer damping. and this paper addresses a design strategy of laminated composite under flexural vibrations with constrained layer damping.

  • PDF

Design of an Active Damping Layer Using Topology Optimization (위상 최적화를 이용한 능동 감쇠층의 설계)

  • 김태우;김지환
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • /
    • pp.660-664
    • /
    • 2003
  • The optimal thickness distribution of an active damping layer is sought so that it satisfies a certain constraint on the dynamic performance of a system minimizing control efforts. To obtain a topologically optimized configuration, which includes size and shape optimization, thickness of the active damping layer is interpolated using linear functions. With the control energy as the objective function to be minimized, the state error energy is introduced as the dynamic performance criterion for the system and used lot a constraint. The optimal control gains are evaluated from LQR simultaneously as the optimization of the layer position proceeds. From numerical simulation, the topologically optimized distribution of the active damping layer shows the same dynamic performance and cost as the Idly covered counterpart, which is optimized only in terms of control gains, with less amount of the layer.

  • PDF

High performance of inverted polymer solar cells

  • Lee, Hsin-Ying;Lee, Ching-Ting;Huang, Hung-Lin
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • /
    • pp.61.2-61.2
    • /
    • 2015
  • In the past decades, green energy, such as solar energy, wind power, hydropower, biomass energy, geothermal energy, and so on, has been widely investigated and developed to solve energy shortage. Recently, organic solar cells have attracted much attention, because they have many advantages, including low-cost, flexibility, light weight, and easy fabrication [1-3]. Organic solar cells are as a potential candidate of the next generation solar cells. In this abstract, to improve the power conversion efficiency and the stability, the inverted polymer solar cells with various structures were developed [4-6]. The novel cell structures included the P3HT:PCBM inverted polymer solar cells with AZO nanorods array, with pentacene-doped active layer, and with extra P3HT interfacial layer and PCBM interfacial layer. These three difference structures could respectively improve the performance of the P3HT:PCBM inverted polymer solar cells. For the inverted polymer solar cells with AZO nanorods array as the electronic transportation layer, by using the nanorod structure, the improvement of carrier collection and carrier extraction capabilities could be expected due to an increase in contact area between the nanorod array and the active layer. For the inverted polymer solar cells with pentacene-doped active layer, the hole-electron mobility in the active layer could be balanced by doping pentacene contents. The active layer with the balanced hole-electron mobility could reduce the carrier recombination in the active layers to enhance the photocurrent of the resulting inverted polymer solar cells. For the inverted polymer solar cells with extra P3HT and PCBM interfacial layers, the extra PCBM and P3HT interfacial layers could respectively improve the electron transport and hole transport. The extra PCBM interfacial layer served another function was that led more P3HT moving to the top side of the absorption layer, which reduced the non-continuous pathways of P3HT. It indicated that the recombination centers could be further reduced in the absorption layer. The extra P3HT interfacial layer could let the hole be more easily transported to the MoO3 hole transport layer. The high performance of the novel P3HT:PCBM inverted polymer solar cells with various structures were obtained.

  • PDF

Low Reverse Saturation Current Density of Amorphous Silicon Solar Cell Due to Reduced Thickness of Active Layer

  • Iftiquar, S M;Yi, Junsin
    • Journal of Electrical Engineering and Technology
    • /
    • v.11 no.4
    • /
    • pp.939-942
    • /
    • 2016
  • One of the most important characteristic curves of a solar cell is its current density-voltage (J-V) curve under AM1.5G insolation. Solar cell can be considered as a semiconductor diode, so a diode equivalent model was used to estimate its parameters from the J-V curve by numerical simulation. Active layer plays an important role in operation of a solar cell. We investigated the effect thicknesses and defect densities (Nd) of the active layer on the J-V curve. When the active layer thickness was varied (for Nd = 8×1017 cm-3) from 800 nm to 100 nm, the reverse saturation current density (Jo) changed from 3.56×10-5 A/cm2 to 9.62×10-11 A/cm2 and its ideality factor (n) changed from 5.28 to 2.02. For a reduced defect density (Nd = 4×1015 cm-3), the n remained within 1.45≤n≤1.92 for the same thickness range. A small increase in shunt resistance and almost no change in series resistance were observed in these cells. The low reverse saturation current density (Jo = 9.62×10-11 A/cm2) and diode ideality factor (n = 2.02 or 1.45) were observed for amorphous silicon based solar cell with 100 nm thick active layer.

Analysis and active control for wind induced vibration of beam with ACLD patch

  • Li, Jinqiang;Narita, Yoshihiro
    • Wind and Structures
    • /
    • v.17 no.4
    • /
    • pp.399-417
    • /
    • 2013
  • The structural vibration suppression with active constrained layer damping (ACLD) was widely studied recently. However, the literature seldom concerned with the vibration control on flow-induced vibration using active constrained layer. In this paper the wind induced vibration of cantilevered beam is analyzed and suppressed by using random theory together with a velocity feedback control strategy. The piezoelectric material and frequency dependent viscoelastic layer are used to achieve effective active damping in the vibration control. The transverse displacement and velocity in time and frequency domains, as well as the power spectral density and the mean-square value of the transverse displacement and velocity, are formulated under wind pressure at variable control gain. It is observed from the numerical results that the wind induced vibration can be significantly suppressed by using a small outside active voltage on the constrained layer.

Influence of Growth Temperature for Active Layer and Buffer Layer Thickness on ZnO Nanocrystalline Thin Films Synthesized Via PA-MBE

  • Park, Hyunggil;Kim, Younggyu;Ji, Iksoo;Kim, Soaram;Lee, Sang-Heon;Kim, Jong Su;Leem, Jae-Young
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • /
    • pp.203.1-203.1
    • /
    • 2013
  • Zinc oxide (ZnO) nanocrystalline thin films on various growth temperatures for active layer and different buffer layer thickness were grown by plasma-assisted molecular beam epitaxy (PA-MBE) on Si substrates. The ZnO active layer were grown with various growth temperature from 500 to $800^{\circ}C$ and the ZnO buffer layer were grown for different time from 5 to 40 minutes. To investigate the structural and optical properties of the ZnO thin films, scanning electron microscope (SEM), X-ray diffractometer (XRD), and photoluminescence (PL) spectroscopy were used, respectively. In the SEM images, the ZnO thin films have high densification of grains and good roughness and uniformity at $800^{\circ}C$ for active layer growth temperature and 20 minutes for buffer layer growth time, respectively. The PL spectra of ZnO buffer layers and active layers display sharp near band edge (NBE) emissions in UV range and broad deep level emissions (DLE) in visible range. The intensity of NBE peaks for the ZnO thin films significantly increase with increase in the active layer growth temperature. In addition, the NBE peak at 20 minutes for buffer layer growth time has the largest emission intensity and the intensity of DLE peaks decrease with increase in the growth time.

  • PDF

A Protective Layer on the Active Layer of Al-Zn-Sn-O Thin-Film Transistors for Transparent AMOLEDs

  • Cho, Doo-Hee;KoPark, Sang-Hee;Yang, Shin-Hyuk;Byun, Chun-Won;Cho, Kyoung-Ik;Ryu, Min-Ki;Chung, Sung-Mook;Cheong, Woo-Seok;Yoon, Sung-Min;Hwang, Chi-Sun
    • Journal of Information Display
    • /
    • v.10 no.4
    • /
    • pp.137-142
    • /
    • 2009
  • Transparent top-gate Al-Zn-Sn-O (AZTO) thin-film transistors (TFTs) with an $Al_2O_3$ protective layer (PL) on an active layer were studied, and a transparent 2.5-inch QCIF+AMOLED (active-matrix organic light-emitting diode) display panel was fabricated using an AZTO TFT backplane. The AZTO active layers were deposited via RF magnetron sputtering at room temperature, and the PL was deposited via two different atomic-layer deposition (ALD) processes. The mobility and subthreshold slope were superior in the TFTs annealed in vacuum and with oxygen plasma PLs compared to the TFTs annealed in $O_2$ and with water vapor PLs, but the bias stability of the TFTs annealed in $O_2$ and with water vapor PLs was excellent.

Improved Bias Stress Stability of Solution Processed ITZO/IGZO Dual Active Layer Thin Film Transistor

  • Kim, Jongmin;Cho, Byoungdeog
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • /
    • pp.215.2-215.2
    • /
    • 2015
  • We fabricated dual active layer (DAL) thin film transistors (TFTs) with indium tin zinc oxide (ITZO) and indium gallium zinc oxide (IGZO) thin film layers using solution process. The ITZO and IGZO layer were used as the front and back channel, respectively. In order to investigate the bias stress stability of ITZO SAL (single active layer) and ITZO/IGZO DAL TFT, a gate bias stress of 10 V was applied for 1500 s under the dark condition. The SAL TFT composed of ITZO layer shows a poor positive bias stability of ${\delta}VTH$ of 13.7 V, whereas ${\delta}VTH$ of ITZO/IGZO DAL TFT was very small as 2.6 V. In order to find out the evidence of improved bias stress stability, we calculated the total trap density NT near the channel/gate insulator interface. The calculated NT of DAL and SAL TFT were $4.59{\times}10^{11}$ and $2.03{\times}10^{11}cm^{-2}$, respectively. The reason for improved bias stress stability is due to the reduction of defect sites such as pin-hole and pores in the active layer.

  • PDF