• Title/Summary/Keyword: Oxide Films

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Comparison of transparent conductive indium tin oxide, titanium-doped indium oxide, and fluorine-doped tin oxide films for dye-sensitized solar cell application

  • Kwak, Dong-Joo;Moon, Byung-Ho;Lee, Don-Kyu;Park, Cha-Soo;Sung, Youl-Moon
    • Journal of Electrical Engineering and Technology
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    • v.6 no.5
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    • pp.684-687
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    • 2011
  • In this study, we investigate the photovoltaic performance of transparent conductive indium tin oxide (ITO), titanium-doped indium oxide (ITiO), and fluorine-doped tin oxide (FTO) films. ITO and ITiO films are prepared by radio frequency magnetron sputtering on soda-lime glass substrate at $300^{\circ}C$, and the FTO film used is a commercial product. We measure the X-ray diffraction patterns, AFM micrographs, transmittance, sheet resistances after heat treatment, and transparent conductive characteristics of each film. The value of electrical resistivity and optical transmittance of the ITiO films was $4.15{\times}10^{-4}\;{\Omega}-cm$. The near-infrared ray transmittance of ITiO is the highest for wavelengths over 1,000 nm, which can increase dye sensitization compared to ITO and FTO. The photoconversion efficiency (${\eta}$) of the dye-sensitized solar cell (DSC) sample using ITiO was 5.64%, whereas it was 2.73% and 6.47% for DSC samples with ITO and FTO, respectively, both at 100 mW/$cm^2$ light intensity.

Characteristics of Reoxidized-Nitrided-Oxide Films Prepared by Sequential Rapid Thermal Oxidation and Nitridation (연속적 급속열처리법에 의한 재산화질화산화막의 특성)

  • 노태문;이경수;이중환;남기수
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.5
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    • pp.729-736
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    • 1990
  • Oxide (RTO), nitrided-oxide(NO), and reoxidized-nitrided-oxide(ONO) films were formed by sequential rapid thermal processing. The film composition was investigated by Auger electron spectroscopy(AES). The Si/SiO2 interface and SiO2 surface are nitrided more preferentially than SiO2 bulk. When the NO is reoxidized, [N](atomic concentration of N) in the NO film decreased` especially, the decrease of [N] at the surface is considerable. The weaker the nitridation condition is, the larger the increase of thickness is as the reoxidation proceeds. The elelctrical characteristics of RTO, NO, and ONO films were evaluated by 1-V, high frequency (1 MHz) C-V, and high frequency C-V after constant current stress. The ONO film-which has 8 nm thick initial oxide, nitrided in NH3 at 950\ulcorner for 60 s, reoxidized in O2 at 1100\ulcorner for 60 s-shows good electrical characteristics such as higher electrical breakdown voltage and less variation of flat band voltage under high electric field than RTO, and NO films.

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Reliability of MOS Capacitors and MOSFET's with Oxide and Reoxidized-Nitrided-Oxide as Gate Insulators (산화막 및 재산화질화산화막의 MOS 캐패시터와 MOSFET의 신뢰성)

  • 노태문;이경수;유병곤;남기수
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.30A no.11
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    • pp.105-112
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    • 1993
  • Oxide and reoxidized-nitrided-oxide were formed by furnace oxidation and rapid thermal processing (RTP). MOS capacitor and n-MOSFET's with those films as gate insulators were fabricated. The electrical characteristics of insulators were evaluated by current-voltage, high-frequency capacitance-voltage (C-V), and time-dependent dielectrical breakdown (TDDB) measurements. The hot carrier effects of MOSFET's were also investigated. Time-dependent dielectrical breakdown (TDDB) characteristics show that the life time of reoxidized-nitrided-oxide films is about 3 times longer than that of oxides. Hot carrier effects reveal that the life time of MOSFET's with reoxidized-nitrided-oxides is about 3 times longer than that of MOSFET's with oxides. Therefore, it is found that the reliability of dielectric films estimated by the hot carrier effects of MOSFET's is consistent with that of dielectric films from TDDB method.

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STIMULATING NEURAL ELECTRODE-A STUDY ON CHARGE INJECTION PROPERTIES OF IRIDIUM OXIDE FILMS

  • Lee, In-Seop;Ray A. Buchanan;Jim M.Williams
    • Journal of the Korean Vacuum Society
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    • v.4 no.S2
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    • pp.156-162
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    • 1995
  • For a stimulating neural electrode, the charge density should be as large as possible to provide adequate stimulation of the nervous system while allowing for miniaturization of the electrode. Since iridium oxide is able to produce high charge densities while preventing undesirable reactions due to charge storage, it has become a promising material for neural prostheses. Successful production of stable Ir and Ir oxide films on various substrates now limits the use of this material. Ir was deposited on two differently prepared surface of (mirror finish, passivation) surgical Ti-6AI-4V with several methods. Ion beam mixing of sputter deposited Ir films on passivated Ti-6AI-4V produced stable and good adherent Ir films. It was found that the increase in charge density of pure Ir on continuous cyclingis due to the accumulation of the oxide phase ( associated with a large surface area) in which the valence state of iridium changes and the double-layer capacitance increases. This study also showed that the double layer capacitance is equally or even more responsible for the high charge density of anodically formed Ir oxide.

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Current Status of Low-temperature TCO Electrode for Solar-cell Application: A Short Review (고효율 태양전지 적용을 위한 저온 투명전극 소재 연구현황 리뷰)

  • Park, Hyeongsik;Kim, Youngkuk;Oh, Donghyun;Pham, Duy Phong;Song, Jaechun;Yi, Junsin
    • New & Renewable Energy
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    • v.17 no.1
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    • pp.1-6
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    • 2021
  • Transparent conducting oxide (TCO) films have been widely used in optoelectronic devices, such as OLEDs, TFTs, and solar cells. However, thin films of indium tin oxide (ITO) have few disadvantages pertaining to process parameters such as substrate temperature and sputtering power. In this study, we investigated the requirements for using TCO films in silicon-based solar cells and the best alternative TCO materials to improve their efficiency. Moreover, we discussed the current status of high-efficiency solar cells using low-temperature TCO films such as indium zinc oxide and Zr-doped indium oxide.

Characterization and Fabrication of Tin Oxide Thin Film by RF Reactive Sputtering (RF Reactive Sputtering법에 의한 산화주석 박막의 제조 및 특성)

  • Kim, Young-Rae;Kim, Sun-Phil;Kim, Sung-Dong;Kim, Sarah Eun-Kyung
    • Korean Journal of Materials Research
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    • v.20 no.9
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    • pp.494-499
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    • 2010
  • Tin oxide thin films were prepared on borosilicate glass by rf reactive sputtering at different deposition powers, process pressures and substrate temperatures. The ratio of oxygen/argon gas flow was fixed as 10 sccm / 60 sccm in this study. The structural, electrical and optical properties were examined by the design of experiment to evaluate the optimized processing conditions. The Taguchi method was used in this study. The films were characterized by X-ray diffraction, UV-Vis spectrometer, Hall effect measurements and atomic force microscope. Tin oxide thin films exhibited three types of crystal structures, namely, amorphous, SnO and $SnO_2$. In the case of amorphous thin films the optical band gap was widely spread from 2.30 to 3.36 eV and showed n-type conductivity. While the SnO thin films had an optical band gap of 2.24-2.49 eV and revealed p-type conductivity, the $SnO_2$ thin films showed an optical band gap of 3.33-3.63 eV and n-type conductivity. Among the three process parameters, the plasma power had the most impact on changing the structural, electrical and optical properties of the tin oxide thin films. It was also found that the grain size of the tin oxide thin films was dependent on the substrate temperature. However, the substrate temperature has very little effect on electrical and optical properties.

Electrical and Optical Properties of IZO Films Deposited on Polynorbornene Substrate (Polynorbornene 기판 위에 증착된 IZO 필름의 전기 및 광학적 특성연구)

  • Park, Sung-Hwan;Ha, KiRyong
    • Applied Chemistry for Engineering
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    • v.20 no.6
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    • pp.612-616
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    • 2009
  • Transparent conductive oxide (TCO) films have been widely used in the field of flat panel display industry. Transparent conductive indium zinc oxide (IZO) thin films with excellent chemical stability have attracted much attention as an alternative material for indium tin oxide (ITO) films. In this study, using a $In_2O_3$ and ZnO powder mixture with a ratio of 90 : 10wt% as a target, IZO films were prepared on polynorbornene (PNB) substrates by electron beam evaporation. The effect of substrate temperature and $O_2$ introduction flow rate were investigated in terms of electrical and optical properties of deposited IZO films. The best electrical and optical properties we obtained from this study were sheet resistance value of $5.446{\times}10^2{\Omega}/{\boxempty}$ and optical transmittance of 87.4% at 550 nm at $O_2$ introduction flow rate of 4 sccm, deposition rate of $2{\AA}$/sec, thickness of 1000 $\AA$ and substrate temperature of $150^{\circ}C$.

Durability Improvement of Electrochromic Tungsten Oxides Films

  • Yang, J.Y.;Kim, J.W.;Kang, G.H.;K.D.Ko;Lee, G.D.
    • Proceedings of the Korean Vacuum Society Conference
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    • 1999.07a
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    • pp.157-157
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    • 1999
  • Electrochromic tungsten oxide films were prepared by the electron beam deposition, and the dependence of the electrochemical stability and the optical properties on the titanium concentration, and on the annealing temperature, that was investigated. coloring and bleaching experiments were repeated by cyclic voltammetry in a propylene carbonate solution of LiClO4. Spectrometry was used to assess the stability of the transmittance in the degraded films. Tungsten oxide films with titanium contents of about 10~15 mol% were found to be most stable, undergoing the least degradation during the repeated for coloring and bleaching cycles. The reason for this small amount of degradation was the reduction of lithium ion trapping sites in the films, which results in an increased durability. Tungsten oxide films with titanium contents of about 20 mol% were annealed at 20$0^{\circ}C$ for 1 hour, and this results showed that durability of films were increased.

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Highly sensitive gas sensor using hierarchically self-assembled thin films of graphene oxide and gold nanoparticles

  • Ly, Tan Nhiem;Park, Sangkwon
    • Journal of Industrial and Engineering Chemistry
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    • v.67
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    • pp.417-428
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    • 2018
  • In this study, we fabricated hierarchically self-assembled thin films composed of graphene oxide (GO) sheets and gold nanoparticles (Au NPs) using the Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS) techniques and investigated their gas-sensing performance. First, a thermally oxidized silicon wafer ($Si/SiO_2$) was hydrophobized by depositing the LB films of cadmium arachidate. Thin films of ligand-capped Au NPs and GO sheets of the appropriate size were then sequentially transferred onto the hydrophobic silicon wafer using the LB and the LS techniques, respectively. Several different films were prepared by varying the ligand type, film composition, and surface pressure of the spread monolayer at the air/water interface. Their structures were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), and their gas-sensing performance for $NH_3$ and $CO_2$ was assessed. The thin films of dodecanethiol-capped Au NPs and medium-sized GO sheets had a better hierarchical structure with higher uniformity and exhibited better gas-sensing performance.

Fabrication of IGZO-based Oxide TFTs by Electron-assisted Sputtering Process

  • Yun, Yeong-Jun;Jo, Seong-Hwan;Kim, Chang-Yeol;Nam, Sang-Hun;Lee, Hak-Min;O, Jong-Seok;Kim, Yong-Hwan
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.273.2-273.2
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    • 2014
  • Sputtering process has been widely used in Si-based semiconductor industry and it is also an ideal method to deposit transparent oxide materials for thin-film transistors (TFTs). The oxide films grown at low temperature by conventional RF sputtering process are typically amorphous state with low density including a large number of defects such as dangling bonds and oxygen vacancies. Those play a crucial role in the electron conduction in transparent electrode, while those are the origin of instability of semiconducting channel in oxide TFTs due to electron trapping. Therefore, post treatments such as high temperature annealing process have been commonly progressed to obtain high reliability and good stability. In this work, the scheme of electron-assisted RF sputtering process for high quality transparent oxide films was suggested. Through the additional electron supply into the plasma during sputtering process, the working pressure could be kept below $5{\times}10-4Torr$. Therefore, both the mean free path and the mobility of sputtered atoms were increased and the well ordered and the highly dense microstructure could be obtained compared to those of conventional sputtering condition. In this work, the physical properties of transparent oxide films such as conducting indium tin oxide and semiconducting indium gallium zinc oxide films grown by electron-assisted sputtering process will be discussed in detail. Those films showed the high conductivity and the high mobility without additional post annealing process. In addition, oxide TFT characteristics based on IGZO channel and ITO electrode will be shown.

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