• 마이크로전자및패키징학회지
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• 제14권3호
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• pp.15-20
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• 2007

플라스틱 기판에 적용이 가능한 최대 공정온도 $270^{\circ}C$ 이하에서 ZnO-TFT 소자를 제작하였다. ZnO-TFT 소자는 bottom gate 구조로 제작되었으며, ICP-CVD로 형성된 $SiO_2$ 산화물 게이트 공정을 제외하고는 모든 박막증착 공정은 RF-magnetron sputtering process를 이용하였다. ZnO 박막은 Ar과 $O_2$ gas 유량의 비율에 따라 여러 가지 조건에서 RF-magnetron sputtering 시스템을 이용하여 상온에서 증착하였다. Ar과 $O_2$ gas의 비율에 따라 제작된 TFT 소자는 모두 enhancement 모드의 소자특성을 나타내었고, 또한 가시광선영역에 있어 80% 이상의 높은 투과율을 보였다. ZnO 증착시 순수 Ar을 사용하여 제작된 ZnO-TFT의 경우에, $1.2\;cm^2/Vs$의 field effect mobility, 8.5 V의 threshold voltage, 그리고 $5{\times}10^5$의 높은 on/off ratio, 1.86 V/decade의 swing voltage로 가장 우수한 전기적 특성을 보였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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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.

• 한국소음진동공학회논문집
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• 제15권2호
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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.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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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.

• 한국전기전자재료학회논문지
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• 제20권11호
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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.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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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.

• 센서학회지
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• 제28권2호
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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.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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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.