• 태양에너지
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• 제19권1호
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• pp.29-36
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• 1999

ZnO/n-Si junctions were fabricated by spin coating with ZnO precursor produced by the sol-gel process. In order to increase the electrical conductivity of ZnO films, the films were n-doped with Al impurity and subsequently annealed at about $450^{\circ}C$ under reducing environments. The ohmic contacts between n-Si and AI for a bottom electrode were successfully fabricated by doping the rear surface of Si substrate with phosphorous atoms. The front surface of the substrate was also doped with phosphorous atoms for improving the efficiency of the solar cells. Consequently, conversion efficiencies ranging up to about 5.3% were obtained. These efficiencies were found to decrease slowly with time because of the oxide films formed at the ZnO/Si interface upon oxygen penetration through the porous ZnO. Oxygen barrier layers could be necessary in order to prevent the reduction of conversion efficiencies.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권1호
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• pp.26-29
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• 2006

Transparent ZnO thin films were prepared by KrF pulsed laser deposition (PLD) technique and applied to a bottom-gate type thin film transistor device as an active channel layer. A high conductive crystalline Si substrate was used as an metal-like bottom gate and SiN insulating layer was then deposited by LPCVD(low pressure chemical vapour deposition). An aluminum layer was then vacuum evaporated and patterned to form a source/drain metal contact. Oxygen partial pressure and substrate temperature were varied during the ZnO PLD deposition process and their influence on the thin film properties were investigated by X-ray diffraction(XRD) and Hall-van der Pauw method. Optical transparency of the ZnO thin film was analyzed by UV-visible phometer. The resulting ZnO-TFT devices showed an on-off ration of $10^6$ and field effect mobility of 2.4-6.1 $cm^2/V{\cdot}s$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.256-256
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• 2008

We report epitaxial growth of ZnO thin films on (100) single-crystalline $LaAlO_3$ (LAO) substrates using pulsed laser deposition (PLD) at different substrate temperatures (400~$800^{\circ}C$). The structural and electrical properties of the films have been investigated by means of X-ray diffraction (XRD), atomic force microscope (AFM), transmission line method (TLM). The poly-crystalline of $\alpha$- and c-axis oriented ZnO film was formed at lower deposition temperature ($T_s$) of $400^{\circ}C$. At higher $T_s$, however, the films exhibit single-crystalline of $\alpha$-axis orientation represented by ZnO[$\bar{1}11$ || LAO <001>. The electrical properties of ZnO thin films depend upon their crystalline orientation, showing lower electrical resistivity values for $\alpha$-axis oriented ZnO films.

• 통합자연과학논문집
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• 제9권4호
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• pp.223-227
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• 2016

The Zn, Sn, and ZnSn thin films were deposited on Si(100) substrate using radio frequency (RF) magnetron co-sputtering method. A surface profiler and X-ray photoelectron spectroscopy (XPS) were used to investigate the Zn, Sn, and ZnSn thin films. Thickness of the thin films was measured by a surface profiler. The deposition rates of pure Zn and Sn thin films were calculated with thickness and sputtering time for optimization. From the survey XPS spectra, we could conclude that the thin films were successfully deposited on Si(100) substrate. The chemical environment of the Zn and Sn was monitored with high resolution XPS spectra in the binding energy regions of Zn 2p, Sn 3d, O 1s, and C 1s.

• 마이크로전자및패키징학회지
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• 제16권4호
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• pp.17-22
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• 2009

Two different organic-inorganic hybrid thin film transistors (OITFTs) with the structures of glass/ITO/ZnO/PMMA/Al (staggered structure) and glass/ITO/PMMA/ZnO/Al (inverted staggered structure), were fabricated and their electrical and structural properties were compared. The ZnO thin films used as active channel layers were deposited by the atomic layer deposition (ALD) method at a temperature of $100^{\circ}C$. To investigate the effect of the substrates on their properties, the ZnO films were deposited on bare glass, PMMA/glass and ITO/glass substrates and their crystal properties and surface morphologies were analyzed. The structural properties of the ZnO films varied with the substrate conditions. The ZnO film deposited on the ITO/glass substrate showed better crystallinity and morphologies, such as a higher preferred c-axis orientation, lower FWHM value and larger particle size compared with the one deposited on the PMMA/glass substrate. The field effect mobility ($\mu$), threshold voltage ($V_T$) and $I_{on/off}$ switching ratio for the OITFT with the staggered structure were about $0.61\;cm^2/V{\cdot}s$, 5.5 V and $10^2$, whereas those of the OITFT with the inverted staggered structure were found to be $0.31\;cm^2/V{\cdot}s$, 6.8 V and 10, respectively. The improved electrical properties for the staggered OITFTs may originate from the improved crystal properties and larger particle size of the ZnO active layer.

• 한국광학회지
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• 제7권2호
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• pp.174-180
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• 1996

광학박막의 미세구조가 그것이 증착된 유리기판의 열확산도에 미치는 영향을 조사하기 위하여 Ar-ion레이저를 광원으로 하는 교류열량계를 직접 제작하여 광학박막으로 널리 쓰이는 ZnS박막의 증착속도를 각각 5.angs./s, 10.angs./s, 20.angs./s, 40.angs./s으로 하여 유리기판 위에 제작한 후 시편의 면에 평행한 방향의 열확산도를 측정한 결과 시편의 온도가 증가할수록 열확산도는 감소하였고 증착속도가 20.angs./s일 때 열확산도가 가장 크며 증착속도에 따라 최대 약 27%의 차이를 나타내었다.

• Applied Microscopy
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• 제25권3호
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• pp.82-89
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• 1995

지금까지의 실험결과에서 다음과 같은 요약할 수 있다. 1) 사원계 $Zn_{1-x}Mg_{x}S_y$ $S_{1-y}$(x=0.13, y=0.16) 에피층은 다소 불규칙한 성장을 나타내어 역삼각형의 결함과 길고 직선인 적층결함으로 형성된 수지상 형태가 발견되었다. 2)역삼각형 결함은 {111}면에 형성된 적층결함으로 둘러싸여 있고 내부에는 결함이 없으나 계면과 수직인 방향인 <001>방향으로 콘트라스트 차이를 이루는 밴드가 형성되었다. 3) 기판과 정합을 이루고 있고 결함이 없는 ZnSe 버퍼 층이 관찰되었으며 결함 및 므와레 줄무늬는 버퍼층과 4원계 에피층과의 계면에서 형성된다. 4) 4원계 에피층에 형성된 적층결함은 Mg 원소의 효과로 길이가 60nm 이상 폭이 40nm 이상의 넓은 간격을 이루고 있다. 5) 긴 적층결함으로 둘러쌓인 수지상 구조에는 국부적으로 주기를 이루며 강한 콘트라스트 차이를 나타내는 줄무늬가 관찰되는데, 이는 Mg 및 S의 국부적인 화학적 조성차이에 기인한 탄성 변형 효과로 생각된다.

• 전기학회논문지
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• 제59권1호
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• pp.108-112
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• 2010

Design of experiment (DOE) method is employed for a systematic and highly efficient optimization of Ga-doped ZnO thin films synthesized by pulsed laser deposition (PLD) process. We sequentially adopted fractional-factorial design (FD) and central composite design (CCD) of the DOE methods. In fractional-FD stage, significant factors to make conductive electrode are found to target-substrate (T-S) distance and oxygen partial pressure. Moreover, correlation among the process factors is elucidated using surface profile modeling. Electrical properties of the GZO films grown on a glass substrate had been optimized to find that the lowest electrical resistivity of about $1.8'10^{-4}Wcm$ which was acquired with the T-S distance and the oxygen pressure of 4 cm and 7 mTorr, respectively. During the DOE-fueled optimization process, the transparency of the GZO films is ensured higher than 85 %.

• Current Optics and Photonics
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• 제7권6호
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• pp.738-744
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• 2023

Graphene-based saturable absorbers (SAs) are widely used as laser mode-lockers at various laser oscillators. In particular, transmission-type graphene-SAs with ultrabroad spectral coverage are typically manufactured on transparent substrates with low nonlinearity to minimize the effects on the oscillators. Here, we developed two types of transmitting graphene SAs based on CaF₂ and ZnSe. Using the graphene-SA based on CaF₂, a passively mode-locked mid-infrared Cr:ZnS laser delivers relatively long 540 fs pulses with a maximum output power of up to 760 mW. In the negative net cavity dispersion regime, the pulse width was not reduced further by inhomogeneous group delay dispersion (GDD) compensation. In the same laser cavity, we replaced only the graphene-SA based on CaF₂ with the SA based on ZnSe. Due to the additional self-phase modulation effect induced by the ZnSe substrate with high nonlinearity, the stably mode-locked Cr:ZnS laser produced Fourier transform-limited ~130 fs near 2,340 nm. In the stable single-pulse operation regime, average output powers up to 635 mW at 234 MHz repetition rates were achieved. To our knowledge, this is the first attempt to achieve shorter pulse widths from a polycrystalline Cr:ZnS laser by utilizing the graphene deposited on the substrate with high nonlinearity.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.216-217
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• 2008

Zinc-oxide films were deposited by pulsed laser deposition (PLD) technique using doped ZnO target (mixed $In_2O_3$ 0.1, 0.3, 0.6 at. % - atomic percentage) on the p-type Si(111) substrate. A little Indium has added at the n-ZnO films for the electron concentration control and enhanced the electrical properties. Also, post thermal annealed ZnO films are shown an enhanced structural and controled electron concentration by the annealing condition for the hetero junction diode of a better emitting characteristics. The electrical and the diode characteristics of the ZnO films were investigated by using Hall effect measurement and current-voltage measurement.