• 전기학회논문지
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• 제56권10호
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• pp.1782-1785
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• 2007

In this paper, the effect of substrate temperature on structural, electrical and optical properties of aluminium-doped zinc oxide (AZO) films were investigated. AZO thin films were prepared on glass substrate by pulsed DC magnetron sputtering technique. The properties of AZO were measured by using XRD, AFM, UV spectrophotometer, and hall effect measurement system. The resistivity of AZO films was improved under the condition of high substrate temperature. The resistivity decreased from $9.95{\times}10^{-2}\;{\Omega}-cm\;to\;1.1{\times}10^{-3}\;{\Omega}-cm$ as a result of high substrate temperature and the average transmittances in visible range were above 80%.

• Transactions on Electrical and Electronic Materials
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• 제7권1호
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• pp.36-41
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• 2006

In this paper, the time evolution of undoped GaN epilayers on a low-temperature GaN buffer layer grown on c-plane sapphire at a low pressure of 300 Torr was studied via a two-step growth condition in a horizontal MOCVD reactor. As a function of the growth time at a high-temperature, the surface morphology, structural quality, and optical and electrical properties were investigated using atomic force microscopy, high-resolution x-ray diffraction, photoluminescence, and Hall effect measurement, respectively. The root-mean-square roughness showed a drastic decrease after a certain period of surface roughening probably due to the initial island growth. The surface morphology also showed the island coalescence and the subsequent suppression of three-dimensional island nucleation. The structural quality of the GaN epilayer was improved with increasing growth time considering the symmetrical (002) and asymmetrical (102) rocking curves. The variations of room-temperature photoluminescence, background carrier concentration, and Hall mobility were measured and discussed.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.401-401
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• 2011

In this work, we deposited Al2O3doped ZnO (AZO) thin films by direct current (DC) magnetron sputtering method with a $40^{\circ}$ tilted target, for application in the front layer of thin film solar cell. Wet chemical etching behavior of AZO films was also investigated. In order to optimize textured AZO films, oxalic acid ($C_2H_2O_4$)has been used as wet etchant of AZO film. In this experiment we used 0.001% concentration of oxalic acid various etching time, that showed an anisotropy in etching texture of AZO films. Electrical resistivity, Hall mobility and carrier concentration measurements are performed by using the Hall measurement, that are $6{\times}10^{-4}{\Omega}cm$, $20{\sim}25cm^2/V-s$ and $4{\sim}6{\times}10^{20}$, respectively.

• 한국세라믹학회지
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• 제36권1호
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• pp.55-60
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• 1999

Hexamethyldisilane(Si2(CH3)6)의 single precursor를 출발원료로 사용하여 화학기상증착법으로 Si 기판위에 buffer층의 형성 없이 $\beta$-SiC의 박막을 증착하였다. Si 기판과 SiO2 mask에서 SiC 박막 증착의 선택성을 위하여 HCI의 식각 가스를 도입하였고 출발원료와 HCI 가스의 공급방법을 변화시켰다. SiC 박막 증착 과정에서 HCI 가스의 도입이 막의 표면 조도에 미치는 영향을 조사하였고 Hall 측정을 통하여 SiC 막의 전기적 특성을 조사하였다.

• Carbon letters
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• 제13권1호
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• pp.44-47
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• 2012

We analyzed the effect of etchants for metal catalysts in terms of the characteristics of resulting graphene films, such as sheet resistance, hall mobility, transmittance, and carrier concentration. We found the residue of $FeCl_3$ etchant degraded the sheet resistance and mobility of graphene films. The residue was identified as an iron oxide containing a small amount of Cl through elemental analysis using X-ray photoelectron spectroscopy. To remove this residue, we provide an alternative etching solution by introducing acidic etching solutions and their combinations ($HNO_3$, HCl, $FeCl_3$ + HCl, and $FeCl_3+HNO_3$). The combination of $FeCl_3$ and acidic solutions (HCl and $HNO_3$) resulted in more enhanced electrical properties than pure etchants, which is attributed to the elimination of left over etching residue, and a small amount of amorphous carbon debris after the etching process.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.313-313
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• 2013

For high-performance TFT (Thin film transistor), poly-crystalline semiconductor thin film with low resistivity and high hall carrier mobility is necessary. But, conventional SPC (Solid phase crystallization) process has disadvantages in fabrication such as long annealing time in high temperature or using very expensive Excimer laser. On the contrary, MIC (Metal-induced crystallization) process enables semiconductor thin film crystallization at lower temperature in short annealing time. But, it has been known that the poly-crystalline semiconductor thin film fabricated by MIC methods, has low hall mobility due to the residual metals after crystallization process. In this study, Ni metal was shallow implanted using PIII&D (Plasma Immersion Ion Implantation & Deposition) technique instead of depositing Ni layer to reduce the Ni contamination after annealing. In addition, the effect of external magnetic field during annealing was studied to enhance the amorphous silicon thin film crystallization process. Various thin film analytical techniques such as XRD (X-Ray Diffraction), Raman spectroscopy, and XPS (X-ray Photoelectron Spectroscopy), Hall mobility measurement system were used to investigate the structure and composition of silicon thin film samples.

• 한국진공학회지
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• 제8권4A호
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• pp.445-449
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• 1999

We studied the properties of the InAs epitaxial layers grown of (100)-oriented GaAs ($2^{\circ}$tilted toward[011]) by molecular beam epitaxy. From DCX (double-crystal x0ray), the better crystal quality was shown in InAs epitaxial layers on about 2500$\AA$ GaAs epitaxial layers on GaAs, we obtained the high mobility of InAs epitaxy in As/In BEP ratio (1.2~2.0) from Hall effect measurement. The electron mobility increased as electron concentration increases, until Si cell temperature $960^{\circ}C$$(N_D=2.21\times10^{-17}\textrm{cm}^{-3})$. The mobility decreases as the Si cell temperature increases, at the temperature over $960^{\circ}C$. We obtained the high mobility (1.10$\times$104cm2/V.s) at Si electron concentration of $N_D=2.21\times10^{-17}\textrm{cm}^{-3}$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.137-137
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• 2009

Indium Gallium Zinc Oxide (IGZO) thin films for TFT channel were prepared by using a Facing Target Sputtering (FTS) system. To investigate the effect of oxygen on the optical and the electrical properties of amorphous InGaZnO(a-IGZO), we prepared thin films by FTS system in various oxygen atmospheres at room temperature. As-deposited IZTO thin films were investigated by using a UV/VIS spectrometer, an X-ray diffractometer, a Hall Effect measurement system, and an atomic force microscope. The quantitative analysis of the films was carried out by using the energy dispersive X-ray (EDX) technique for the as-deposited film.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.13-18
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• 2004

It is important to estimate the distribution of intensity of a magnetic field for application of magnetic method to industrial nondestructive evaluation. Magnetic camera provides the distribution of a quantitative magnetic field with homogeneous lift-off and same spatial resolution. Leakage magnetic flux near the crack on the specimen could be amplified by 3-dimensional magnetic fluid and zoom in and out of measurement area. This study introduces the experimental consideration of the effects of lens for concentrating of magnetic flux. The experimental results showed that the magnetic fluid has sufficient lens effect for magnetic camera and effect of improvement in probability of detection.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.25-26
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• 2011

In this paper, we investigated the effect of various annealing processes on the electrical characteristics of oxide thin film transistors (TFTs). When we annealed the TFT devices before and after source/drain (S/D) process, we could observe the different electrical characteristics of oxide TFTs. When we annealed the TFTs after deposition of transparent indium zinc oxide S/D electrodes, the annealing process decreased the contact resistance but increased the resistivity of S/D electrodes. The field effect mobility, subthreshold slope and threshold voltage of the oxide TFTs annealed before and after S/D process were 5.83 and 4.47 $cm^2$/Vs, 1.20 and 0.82 V/dec, and 3.92 and 8.33 V respectively. To analyze the differences, we measured the contact resistances and the carrier concentrations using transfer length method (TLM) and Hall measurement.