• Title/Summary/Keyword: Optical mobility

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Thin Film Transistor Characteristics with ZnO Channel Grown by RF Magnetron Sputtering (RF Magnetron Sputtering으로 증착된 ZnO의 증착 특성과 이를 이용한 Thin Film Transistor특성)

  • Kim, Young-Woong;Choi, Duck-Kyun
    • Journal of the Microelectronics and Packaging Society
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    • v.14 no.3
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    • pp.15-20
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    • 2007
  • Low temperature processed ZnO-TFTs on glass below $270^{\circ}C$ for plastic substrate applications were fabricated and their electrical properties were investigated. Films in ZnO-TFTs with bottom gate configuration were made by RF magnetron sputtering system except for $SiO_2$ gate oxide deposited by ICP-CVD. ZnO channel films were grown on glass with various Ar and $O_2$ flow ratios. All of the fabricated ZnO-TFTs showed perfectly the enhancement mode operation, a high optical transmittance of above 80% in visible ranges of the spectrum. In the ZnO-TFTs with pure Ar process, the field effect mobility, threshold voltage, and on/off ratio were measured to be $1.2\;cm^2/Vs$, 8.5 V, and $5{\times}10^5$, respectively. These characteristic values are much higher than those of the ZnO-TFTs of which ZnO channel layers were processed with additional $O_2$ gas. In addition, ZnO-TFT with pure Af process showed smaller swing voltage of 1.86v/decade compared to those with $Ar+O_2$ process.

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High Transparent, High Mobility MoO3 Intergraded InZnO Films for Use as a Transparent Anode in Organic Solar cells

  • Kim, Hyo-Jung;Kang, Sin-Bi;Na, Seok-In;Kim, Han-Ki
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.343-343
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    • 2014
  • We reported on the electrical, optical, structural and morphological properties fabricated by co-sputtering for use as an anode for organic solar cells (OSCs). By adjusting RF and DC power of $MoO_3$ and IZO targets during co-sputtering, we fabricated the $MoO_3$-IZO electrode with graded content of the $MoO_3$ on the IZO films. At optimized $MoO_3$ thickness of 20 nm, the $MoO_3$ graded IZO electrode showed a higher mobility ($33cm^2/V-Sec$) than directly deposited $MoO_3$ on IZO film ($26cm^2/V-Sec$). At visible range (400nm~800nm), optical transmittance of the $MoO_3$ graded IZO electrode is higher than that of directly deposited $MoO_3$ on IZO film. High mobility of $MoO_3$ graded on IZO is attributed to less interface scattering between $MoO_3$ and IZO. To investigate the feasibility of $MoO_3$ graded IZO films, we fabricated conventional P3HT:PCBM based OSCs with $MoO_3$ graded IZO as a function of MoO3 thickness. The OSC fabricated on the $MoO_3$ graded IZO anode showed a fill factor of 66.53%, a short circuit current of $8.121mA/cm^2$, an open circuit voltage of 0.592 V, and a power conversion efficiency of 3.2% comparable to OSC fabricated on ITO anode and higher than directly deposited $MoO_3$ on IZO film. We suggested possible mechanism to explain the high performance of OSCs with a $MoO_3$ graded IZO.

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Electronic and optical devices based on semiconductor nanowires (반도체 나노선 전자소자 및 광전소자응용)

  • Kil, Sang-Cheol;Sim, Sung-Kju;Kim, Sang-Sig
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.11a
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    • pp.260-263
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    • 2004
  • During the last few years, there have been many efforts on the fabrication of electronic and optical devices based on semiconductor nanowires. Room-temperature ultraviolet lasing in GaN nanowire, ultraviolet light sensing in ZnO nanowire, and dramatically improved hall mobility in Si nanowire have been demonstrated in this article. The studies on semiconductor nanowire based electronic and optical device is reviewed.

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Electrical and optical characteristics of porous 3C-SiC thin films with dopants (도핑량에 따른 다공성 3C-SiC 박막의 전기 및 광학적 특성)

  • Kim, Kan-San;Chung, Gwiy-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.06a
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    • pp.27-27
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    • 2010
  • This paper describes the electrical and optical characteristics of $N_2$ doped porous 3C-SiC films. Average pore diameter is about 30 nm and etched area was increased with $N_2$ doping rate. The mobility was dramatically decreased in porous 3C-SiC. The band gaps of polycrystalline 3C-SiC films and doped porous 3C-SiC were 2.5 eV and 2.7 eV, respectively.

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Design of the Slider and Suspension for 4 × 1 Near-field Probe Array in Micro Optical Disk Drives (마이크로 광디스크 드라이브용 4 × 1 근접장 탐침 어레이를 위한 슬라이더와 서스펜션의 설계)

  • Hong, Eo-Jin;Jung, Min-Su;Oh, Woo-Seok;Park, No-Cheol;Yang, Hyun-Seok;Park, Young-Pil
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.2 s.95
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    • pp.184-191
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    • 2005
  • The near-field scanning micro scope (NSOM) technique is in the spotlight as the next generation storage device. Many different types of read/write mechanism for NSOM have been introduced in the literature. In order for a near-field probe to be successfully implemented in the system, a suitable slider and suspension are needed to be properly designed. The optical slider is designed considering near-filed optics and probe array. The suspension generally supports slider performance, and tracking servo capacity in HDD. Moreover, the suspension for optical slider also should meet the optical characteristics, and is also required to satisfy shock performances for the mobility for the actuator. In this study, the optical slider and the suspension for near-field probe array are designed and analyzed.

Effect of Ar Flow Ratio on the Characteristics of Ga-Doped ZnO Grown by RF Magnetron Sputtering (마그네트론 스퍼터를 이용한 Ar 가스 유량 조절에 따른 GZO의 특성 변화)

  • Jeong, Youngjin;Lee, Seungjin;Son, Changsik
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.11a
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    • pp.62.1-62.1
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    • 2011
  • The structural, optical, and electrical properties of Ga-doped ZnO (GZO) thin films on glass substrates grown by radio-frequency(RF) magnetron sputtering were investigated. The flow ratio of Ar was varied as a deposition parameter for growing high-quality GZO thin films. The structural properties and surface morphologies of GZO were characterized by the X-ray diffraction. To analyze the optical properties of GZO, the optical absorbance was measured in the wavelength range of 300-1100 nm by using UV-VIS spectrophotometer. The optical transmittance, absorption coefficient, and optical bandgap energy of GZO thin films were calculated from the measured data. The crystallinity of GZO thin films is improved and the bandgap energy increases from 3.08 to 3.23eV with the increasing Ar flow ratio from 10 to 100 sccm. The average transmittance of the films is over 88% in the visible range. The lowest resistivity of the GZO is $6.215{\times}10^{-4}{\Omega}{\cdot}cm$ and the hall mobility increases with the increasing Ar flow ratio. We can optimize the characteristics of GZO as a transparent electrode for thin film solar cells by controlling Ar flow ratio during deposition process.

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Properties of ZnO Thin Films Grown by Radio-frequency Magnetron Sputtering in terms of O2/Ar Mixture Flow Ratio (O2/Ar 혼합 유량비를 변수로 갖는 라디오파 마그네트론 스퍼터링으로 성장된 ZnO 박막의 특성)

  • Cho, Shin-Ho
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.20 no.11
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    • pp.932-938
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    • 2007
  • The structural, optical, and electrical properties of ZnO thin films grown on glass by radio-frequency (rf) magnetron sputtering were investigated. The mixture flow ratio of $O_2$ to Ar, which was operated with sputtering gas, was chosen as a parameter for growing high-qualify ZnO thin films. The structural properties and surface morphologies of the thin films were characterized by the X-ray diffraction and the atomic force microscope, respectively. As for the optical properties of the films, the optical absorbance was measured in the wavelength range of 300-1100 nm by using UV-VIS spectrophotometer. The optical transmittance, absorption coefficient, and optical bandgap energy of ZnO thin films were calculated from the measured data. The crystallinity of the films was improved and the bandgap energy was increased from 3.08 eV to 3.23 eV as the oxygen flow ratio was increased from 0 % to 50 %. Furthermore, The ultraviolet and violet luminescences were observed by using photoluminescence spectroscopy. The hall mobility was decreased with the increase of oxygen flow ratio.

Design of the Slider and Suspension for 4x1 Near-field Probe Array in Micro Optical Disk Drives (마이크로 광디스크 드라이브용 4x1 근접장 탐침 어레이를 위한 슬라이더와 서스펜션의 설계)

  • Hong, Eo-Jin;Jung, Min-Su;Oh, Woo-Seok;Park, No-Cheol;Yang, Hyun-Seok;Park, Young-Pil
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.393-398
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    • 2004
  • The near-field scanning micro scope (NSOM) technique is in the spotlight as the next generation storage device. Many different types of read/write mechanism for NSOM have been introduced in the literature. In order for a near-field probe to be successfully implemented in the system, a suitable slider and suspension are needed to be properly designed. The optical slider is designed considering near-filed optics and probe array. The suspension generally supports slider performance, and tracking servo capacity in HDD. Moreover, the suspension for optical slider also should meet the optical characteristics, and is also required to satisfy shock performances for the mobility for the actuator. In this study, the optical slider and the suspension fer near-field probe array are designed and analyzed.

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Effects of Optically-modulated Metal-graphene Contact on the Photoresponsivity of Graphene Photodetectors (빛에 의해 변조되는 금속-그래핀 컨택이 그래핀 포토디텍터의 광응답도에 미치는 영향)

  • Lee, Chang-Ju;Shim, Jae Hoon;Park, Hongsik
    • Journal of Sensor Science and Technology
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    • v.28 no.2
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    • pp.117-120
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    • 2019
  • Graphene is recognized as a promising material for silicon photonics, since it has a wide optical-window that entirely covers the optical communication wavelength region ($1.3{\sim}1.6-{\mu}m$) and extremely high-carrier mobility that makes it possible to fabricate the high-speed photodetectors. However, the maximum absorbance of monolayer graphene is only 2.3%, which limits the photoresponse characteristics of graphene photodetectors. As a result, a low photoresponsivity of graphene photodetector is a critical issue limiting the use of graphene photodetectors in the optical communications field. In this paper, we investigated effects of optically-modulated metal-graphene contact on the photoresponsivity of graphene photodetectors. The optical modulation of the contact resistance mainly determined the photoresponse characteristics of graphene photodetectors. The Ni-contact graphene photodetector which has a characteristic of the significant optical modulation of metal-graphene contact showed a higher photoresponsivity than the Pd-contact device. This work will provide a way to improve the photoresponse characteristics of graphene-based photodetector and contribute to the development of high-speed/high-responsivity graphene photodetector.

Poly-4-vinylphenol and Poly (melamine-co-formaldehyde)-based Tungsten Diselenide (WSe2) Doping Method

  • Nam, Hyo-Jik;Park, Hyung-Youl;Park, Jin-Hong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2015.08a
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    • pp.194.1-194.1
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    • 2015
  • Transition metal dichalcogenide (TMD) with layered structure, has recently been considered as promising candidate for next-generation flexible electronic and optoelectronic devices because of its superior electrical, optical, and mechanical properties.[1] Scalability of thickness down to a monolayer and van der Waals expitaxial structure without surface dangling bonds (consequently, native oxides) make TMD-based thin film transistors (TFTs) that are immune to the short channel effect (SCE) and provide very high field effect mobility (${\sim}200cm^2/V-sec$ that is comparable to the universal mobility of Si), respectively.[2] In addition, an excellent photo-detector with a wide spectral range from ultraviolet (UV) to close infrared (IR) is achievable with using $WSe_2$, since its energy bandgap varies between 1.2 eV (bulk) and 1.8 eV (monolayer), depending on layer thickness.[3] However, one of the critical issues that hinders the successful integration of $WSe_2$ electronic and optoelectronic devices is the lack of a reliable and controllable doping method. Such a component is essential for inducing a shift in the Fermi level, which subsequently enables wide modulations of its electrical and optical properties. In this work, we demonstrate n-doping method for $WSe_2$ on poly-4-vinylphenol and poly (melamine-co-formaldehyde) (PVP/PMF) insulating layer and adjust the doping level of $WSe_2$ by controlling concentration of PMF in the PVP/PMF layer. We investigated the doping of $WSe_2$ by PVP/PMF layer in terms of electronic and optoelectronic devices using Raman spectroscopy, electrical measurements, and optical measurements.

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