• 제목/요약/키워드: hydrogenated amorphous silicon film

검색결과 105건 처리시간 0.023초

능동형 유기 발광 다이오드(AMOLED)에서 발생하는 수소화된 비정질 실리콘 박막 트랜지스터(Hydrogenated Amorphous Silicon Thin Film Transistor)의 이력 (Hysteresis) 현상 (Hysteresis Phenomenon of Hydrogenated Amorphous Silicon Thin Film Transistors for an Active Matrix Organic Light Emitting Diode)

  • 최성환;이재훈;신광섭;박중현;신희선;한민구
    • 전기학회논문지
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    • 제56권1호
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    • pp.112-116
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    • 2007
  • We have investigated the hysteresis phenomenon of a hydrogenated amorphous silicon thin film transistor (a-Si:H TFT) and analyzed the effect of hysteresis phenomenon when a-Si:H TFT is a pixel element of active matrix organic light emitting diode (AMOLED). When a-Si:H TFT is addressed to different starting gate voltages, such as 10V and 5V, the measured transfer characteristics with 1uA at $V_{DS}$ = 10V shows that the gate voltage shift of 0.15V is occurred due to the different quantities of trapped charge. When the step gate-voltage in the transfer curve is decreased from 0.5V to 0.05V, the gate-voltage shift is decreased from 0.78V to 0.39V due to the change of charge do-trapping rate. The measured OLED current in the widely used 2-TFT pixel show that a gate-voltage of TFT in the previous frame can influence OLED current in the present frame by 35% due to the change of interface trap density induced by different starting gate voltages.

a-Si:H Photodiode Using Alumina Thin Film Barrier

  • Hur Chang-Wu;Dimitrijev Sima
    • Journal of information and communication convergence engineering
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    • 제3권4호
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    • pp.179-183
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    • 2005
  • A photodiode capable of obtaining a sufficient photo/ dark current ratio at both forward bias state and reverse bias state is proposed. The photodiode includes a glass substrate, an aluminum film formed as a lower electrode over the glass substrate, an alumina film formed as an insulator barrier over the aluminum film, a hydrogenated amorphous silicon film formed as a photo conduction layer over a portion of the alumina film, and a transparent conduction film formed as an upper electrode over the hydro-generated amorphous silicon film. A good quality alumina $(Al_2O_3)$ film is formed by oxidation of aluminum film using electrolyte solution of succinic acid. Alumina is used as a potential barrier between amorphous silicon and aluminum. It controls dark-current restriction. In case of photodiodes made by changing the formation condition of alumina, we can obtain a stable dark current $(\~10^{-12}A)$ in alumina thickness below $1000{\AA}$. At the reverse bias state of the negative voltage in ITO (Indium Tin Oxide), the photo current has substantially constant value of $5{\times}10^{-9}$ A at light scan of 100 1x. On the other hand, the photo/dark current ratios become higher at smaller thicknesses of the alumina film. Therefore, the alumina film is used as a thin insulator barrier, which is distinct from the conventional concept of forming the insulator barrier layer near the transparent conduction film. Also, the structure with the insulator thin barrier layer formed near the lower electrode, opposed to the ITO film, solves the interface problem of the ITO film because it provides an improved photo current/dark current ratio.

Growth and Characterization of a-Si :H and a-SiC:H Thin Films Grown by RF-PECVD

  • Kim, Y.T.;Suh, S.J.;Yoon, D.H.;Park, M.G.;Choi, W.S.;Kim, M.C.;Boo, J.-H.;Hong, B.;Jang, G.E.;Oh, M.H.
    • 한국표면공학회지
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    • 제34권5호
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    • pp.503-509
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    • 2001
  • Thin films of hydrogenated amorphous silicon (a-Si : H) and hydrogenated amorphous silicon carbide (a-SiC:H) of different compositions were deposited on Si(100) wafer and glass by RF plasma-enhanced chemical vapor deposition (RF-PECVD). In the present work, we have investigated the effects of the RF power on the properties, such as optical band gap, transmittance and crystallinity. The Raman data show that the a-Si:H material consists of an amorphous and crystalline phase for the co-presence of two peaks centered at 480 and $520 cm^{-1}$ . The UV-VIS data suggested that the optical energy band gap ($E_{g}$ ) is not changed effectively with RF power and the obtained $E_{g}$(1.80eV) of the $\mu$c-Si:H thin film has almost the same value of a-Si:H thin film (1.75eV), indicating that the crystallity of hydrogenated amorphous silicon thin film can mainly not affected to their optical properties. However, the experimental results have shown that$ E_{g}$ of the a-SiC:H thin films changed little on the annealing temperature while $E_{g}$ increased with the RF power. The Raman spectrum of the a-SiC:H thin films annealed at high temperatures showed that graphitization of carbon clusters and microcrystalline silicon occurs.

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RF-PECVD에 의해 증착된 a-C:H 박막의 물리적 및 전기적 특성 분석 (Physical and electrical properties of a-C:H deposited by RF-PECVD)

  • 김인준;김용탁;최원석;윤대호;홍병유
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2002년도 하계학술대회 논문집
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    • pp.296-300
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    • 2002
  • Thin films of Hydrogenated amorphous carbon(a-C:H) are generally exhibited by high electrical resistivities from 10$^2$ to 10$\^$16/ Ω$.$cm, resulting in an interesting material for high power, high temperature MIS devices applications. The hydrogenated amorphous carbon(a-C:H) films were deposited on silicon and glass using an rf plasma enhanced CVD method. The resultant film properties were evaluated in the respect of material based on r.f. power variation. The hydrogenated amorphous carbon(a-C:H) films of thickness ranging from 30 to 50 m were deposited at the pressure of 1 ton with the mixture of methane and hydrogen. We have used rf-IR( courier transform IR) and AFM(Atomic force microscopy) for determining physical properties and current-voltage(I-V) measurement for electrical Properties.

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수소기처리에 의한 수소화된 비정질규소의 안정성에 관한 연구 (The Stability of Hydrogenated Amorphous Silicon by Hydrogen Radical Annealing)

  • 이재희;이원식
    • 한국진공학회지
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    • 제5권1호
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    • pp.73-76
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    • 1996
  • We have prepared hydrogenated amophous silicon (a-si : H) films with superlattice structure by hydrogen radical anneling(HRA) technique. We have studied the preparation of a-Si :H films by HRA and the optical & electronic characteristics. Optical band gap and the hydrogen contents in the a Si : H film is decreased as HRA time increased. We first report a -Si : H film prepared by periodicdeposition of a-Si : H layer and HRA have the superlattice structure using TEM . After 1 hour light soaking on the a-Si :H film prepared by HRA, there are no difference in the temperatre dependence of dark conductivity and the conductivity activation energy. An excellent stability for light in a-Si :H films by HRA can be explained using the long-range structural relaxation of the amorphous network and the propertiesof light -induced defects(LID) proposed by Fritzsche.

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The Effect of Hydrogen on the Tribological Properties of Hydrogenated Amorphous Carbon Films

  • Shin, Jong-Han;Lim, Dae-Soon
    • The Korean Journal of Ceramics
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    • 제3권2호
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    • pp.96-100
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    • 1997
  • Hydrogenated amorphous carbon films were deposited on silicon substrates by using an RF PECVD. The hydrogen/methane ratio was varied from 50% to 88% to study the effect of hytdrogen in the film on the tribological properties. The friction and wear behaviors of the deposited films were investigated by ball-on-disk type wear tester. FT-IR spectra were used to characterize the structure of the films. Tribological properties of carbon films were correlated with their structure such as ratio of "polymer-like" stretching type and that of sp2 bonding. The result showed that the annealing caused a decrease in the amount of wear of contacted $Si_3N_4$ balls and a increase in the coefficient of friction. Possible explanation for annealing effect was discussed by the hydrogen desorption.esorption.

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Inverted Staggered-Type 비정질 실리콘 박막트랜지스터의 수치적 분석 (Numerical Analysis of Inverted Staggered-Type Hydrogenated Amorphous Silicon Thin Film Transistor)

  • 오창호;박진석;한민구
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1990년도 추계학술대회 논문집 학회본부
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    • pp.93-96
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    • 1990
  • The characteristics of an inverted staggered-type hydrogenated amorphous silicon thin film transistor has been analyzed by employing numerical simulation. The field effect mobility and threshold voltage are characterized as a function of density of deep and tail states and lattice temperature. It has been found that the density of deep states plays an important role of determining the threshold voltage, while the field effect mobility are very sensitive to the slope of band tail states. Also, the numerically temperature dependence of field effect mobility and threshold voltage has been in good agreements with the experimental results.

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TWO DIMENSIONAL NUMERICAL SIMULATION PROGRAM FOR HYDROGENATED AMORPHOUS SILICON THIN FILM TRANSISTORS

  • Choi, Jong-S.;Neudeck, Gerold W.
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1994년도 추계학술대회 논문집 학회본부
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    • pp.252-257
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    • 1994
  • A non-uniform finite-difference Thin Film Transistor Simulation Program (TFTSP) has been developed for hydrogenated amorphous silicon TFTs. TFTSP was developed to remove as many of simplifying assumptions as possible and to provide flexibility in the modeling of TFTs so that different model assumptions may be analyzed and compared. In order to insure its usefulness and versatility as an analytic and design tool it is important for the code to satisfy a number of conditions. However, at the beginning stage of the program development, this paper shows that the code can compute the static terminal characteristics of a-Si:H TFTs under a wide range of bias conditions to allow for comparison of the model with experiment. Some of those comparisons include transfer characteristics and I-V characteristics. TFTSP will be refined to conveniently model the performances of TFTs of different designs and to analyze many anomalous behaviors and factors of a-Si:H TFTs.

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스퍼터링 및 저압화학기상증착 비정질 실리곤 박막의 고상 결정화 특성 (Characterization of Solid Phase Crystallization in Sputtered and LFCVD Amorphous Silicon Thin Film)

  • 김형택
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 1995년도 추계학술대회 논문집
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    • pp.89-93
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    • 1995
  • Effects of hydrogenation in amorphous silicon rile growths on Solid Phase Crystallization (SPC) was investigated using x-ray diffractometry, energy dispersive Spectroscopy, and Raman spectrum. Interdiffusion of barium(Ba) and aluminum(Al) compounds of corning substrate was observed in both of rf sputtering and LFCVD films under the low temperature(580$^{\circ}C$) annealing. Low degree of crystallinity resulted from the interdiffusion was obtained. Highly applicable degree of crystallinity was obtained through the mechanical damage induced surface activation on amorphous silicon films. X-ray diffraction intensity of (111) orientation was used to characterize the degree of crystallinity of SPC. Nucleation and growth rate in SPC could be controllable through the employed surface treatment. IIydrogenated LPCVD films showed the superior crystallinity to non-hydrogenated sputtering films. Insignificant effects of activation treatment in sputtered film was of activation treatment in sputtered film was observed on SPC.

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광조사에 따른 비정질 실리콘의 열화 (Light-Induced Degradation of Hydrogenated Amorphous Silicon)

  • 박진석;한민구;이정한
    • 대한전자공학회논문지
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    • 제25권5호
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    • pp.501-508
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    • 1988
  • This paper presents the light-induced effects on the elelctrical and optical properties of undoped and doped hydrogenated amorphous silicon films. The changes in the conductivities and the activation energies of various types of a-Si:H films due to the prolonged exposure to light have been characterized as a function of deposition conditions and illumination periods. The dark conductivity changes may be quenched for heavier doped a-Si:H films. We have also analyzed the variations of micro-structure of a-Si:H film such as silicon-hydrogen bondings in the rocking and stretching modes utilizing infrared spectroscopy. From the experimental results, it is elucidated that doping effects must be crucial to the degradations of the fundamental properties of a-Si:H due to light-induced effects.

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