• Transactions of the Korean hydrogen and new energy society
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• v.12 no.3
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• pp.201-209
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• 2001

The change of optical transmittance of $PdH_x$ thin film due to hydrogen concentration change was measured at room temperature. Pd film($312{\AA}$ thick) was made by thermal evaporation on glass substrate. Hydrogen absorption and desorption cycling effect on optical transmittance was measured 4 times in the pressure range between 0 and 640 torr. Ratio of optical transmittance to the change of ln pressure(torr) increases with increasing number of hydrogen A-D cyclings in the ${\beta}$ phase.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.9
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• pp.29-35
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• 1992

Dielectric thin film of N/O (Si$_{3}N_[4}/SIO_{2}$) for high density stacked dynamic-RAM cell was formed by LPCVD and oxidation(Dry & pyrogenic oxidation methods) of the top Si$_{3}N_[4}$ film. The thickness, structure and composition of this film were measured by ellipsometer, high frequency C-V meter, high resolution TEM, AES, and SIMS. The thickness limit of Si$_{3}N_[4}$ film in making thin N/O structure layer was 7nm. In this experiment, the film with thinner than 7nm was not thick enough as oxygen diffusion barrier, and oxygen punched through the film and interfacial oxidation occurred at the phase boundary between Si$_{3}N_[4}$ and polycrystalline silicon electrode.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.211-214
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• 2007

In this paper, the resonance characteristics of ZnO-based film bulk acoustic resonator (FBAR) devices with thick bottom electrode are investigated. The ultra-thin Cr film (300 ${\AA}-thick$) between $SiO_2$ film and W film is formed by a sputtering-deposition in order to enhance the adherence at their interfaces. The resonance frequency of three different resonator devices was observed to be ${\sim}2.7$ GHz, and the resonance characteristics $(S_{11})$ of the FBAR devices were found to have a strong dependence on the thickness of bottom electrode.

• Journal of the Korean Ceramic Society
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• v.31 no.7
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• pp.795-803
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• 1994

Ferroelectric BaTiO3 thin film was produced using BaTi-ethoxide sol. This sol was prepared from BaTi-ethoxide by a partial hydrolysis with ammonia as a basic catalyst and ethylene glycol as a chelating agent. BaTiO3 thin film was prepared from three continuous spin-coating layers of the sol on bare Si(100) wafer at 2500 rpm followed by pyrolysis at $700^{\circ}C$ for 30 min. After the heat treatment, the film was 0.200$\pm$0.010 ${\mu}{\textrm}{m}$ thick and its grain size was 0.059 ${\mu}{\textrm}{m}$. On the other hand, electrical properties were measured for BaTiO3 thin film separately prepared on Au-deposited silicon wafer. The dielectric constant and loss of the BaTiO3 thin film at room temperature was 150~160 and 0.04 respectively, which was measured at 10 kHz and oscillation level of 0.1 V. In the measurements of the dielectric properties at high temperatures, it was observed that the capacitance of the thin film increases steeply, while the dielectric loss reaches maximum around 1$25^{\circ}C$, which corresponds a phase transition from tetragonal to cubic BaTiO3.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.252-257
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• 2004

Nanometer-sized structures are being applied to many devices including micro/nano electronics, optoelectronics, quantum devices, MEMS/NEMS, biosensors, etc. Especially, the thin film with submicron thickness is a basic structure for fabricating these devices, but its mechanical behaviors are not well understood. The mechanical properties of the thin film are different from those of the bulk structure and are difficult to measure because of its handling inconvenience. Several techniques have been applied to mechanical characterization of the thin film, such as nanoindentation test, micro/nano tensile test, strip bending test, etc. In this study, we focus on the strip bending test because of its high accuracy and moderate specimen preparation efforts, and measure Au thin film, which is a very popular material in micro/nano electronic devices. Au film is deposited on Si substrate by evaporation process, of which thickness is 100nm. Using the strip bending test, we obtain elastic modulus, yield and ultimate tensile strength, and residual stress of Au thin film.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.267-270
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• 2003

We have studied the interfacial diffusion phenomena and the role of ${\alpha}-Al_2O_3$ buffer layer as a diffusion barrier in the $Ba-ferrite/SiO_2$ magnetic thin films for high-density recording media. In the interface of amorphous Ba-ferrite ($1900-{\AA}-thick)/SiO_2$ thin film during annealing, the interfacial diffusion started to occur at ${\sim}700^{\circ}C$. As the annealing temperature increased up to $800^{\circ}C$, the interfacial diffusion abruptly proceeded resulting in the high interface roughness and the deterioration of the magnetic properties. In order to control the interfacial diffusion at the high temperature, we introduced ${\alpha}-Al_2O_3$ buffer layer ($110-{\AA}-thick$) in the interface of $Ba-ferrite/SiO_2$ thin film. During the annealing of $Ba-ferrite/{\alpha}-Al_2O_3/SiO_2$ thin film even at ${\sim}800^{\circ}C$, the interface was very smooth. The smooth interface of the film was also clearly shown by the cross-sectional FESEM. The magnetic properties, such as saturation magnetization 3nd intrinsic coercivity, were also enhanced, due to the inhibition of interfacial diffusion by the ${\alpha}-Al_2O_3$ buffer layer. Our study suggests that the ${\alpha}-Al_2O_3$ buffer layer act as a useful interfacial diffusion barrier in the $Ba-ferrite/SiO_2$ thin films.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.493-493
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• 2014

The manufacturing cost of thin-film photovoltics can potentially be lowered by minimizing the amount of a semiconductor material used to fabricate devices. Thin-film solar cells are typically only a few micrometers thick, whereas crystalline silicon (c-Si) wafer solar cells are $180{\sim}300\mu}m$ thick. As such, thin-film layers do not fully absorb incident light and their energy conversion efficiency is lower compared with that of c-Si wafer solar cells. Therefore, effective light trapping is required to realize commercially viable thin-film cells, particularly for indirect-band-gap semiconductors such as c-Si. An emerging method for light trapping in thin film solar cells is the use of metallic nanostructures that support surface plasmons. Plasmon-enhanced light absorption is shown to increase the cell photocurrent in many types of solar cells, specifically, in c-Si thin-film solar cells and in poly-Si thin film solar cell. By proper engineering of these structures, light can be concentrated and coupled into a thin semiconductor layer to increase light absorption. In many cases, silver (Ag) nanoparticles (NP) are formed either on the front surface or on the rear surface on the cells. In case of poly-Si thin film solar cells, Ag NPs are formed on the rear surface of the cells due to longer wavelengths are not perfectly absorbed in the active layer on the first path. In our cells, shorter wavelengths typically 300~500 nm are also not effectively absorbed. For this reason, a new concept of plasmonic nanostructure which is NPs formed both the front - and the rear - surface is worth testing. In this simulation Al NPs were located onto glass because Al has much lower parasitic absorption than other metal NPs. In case of Ag NP, it features parasitic absorption in the optical frequency range. On the other hand, Al NP, which is non-resonant metal NP, is characterized with a higher density of conduction electrons, resulting in highly negative dielectric permittivity. It makes them more suitable for the forward scattering configuration. In addition to this, Ag NP is located on the rear surface of the cell. Ag NPs showed good performance enhancement when they are located on the rear surface of our cells. In this simulation, Al NPs are located on glass and Ag NP is located on the rear Si surface. The structure for the simulation is shown in figure 1. Figure 2 shows FDTD-simulated absorption graphs of the proposed and reference structures. In the simulation, the front of the cell has Al NPs with 70 nm radius and 12.5% coverage; and the rear of the cell has Ag NPs with 157 nm in radius and 41.5% coverage. Such a structure shows better light absorption in 300~550 nm than that of the reference cell without any NPs and the structure with Ag NP on rear only. Therefore, it can be expected that enhanced light absorption of the structure with Al NP on front at 300~550 nm can contribute to the photocurrent enhancement.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.3
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• pp.27-34
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• 2017

We investigated the feasibility of parylene F usage as an intermediate layer between a polydimethylsiloxane (PDMS) substrate and an Au thin-film interconnect as well as the swelling effect of PDMS substrate on the stretchable deformability of an Au thin film. The 150-nm-thick Au film, which was sputtered on a PDMS substrate without a parylene F layer, exhibited an initial resistance of $11.7{\Omega}$ and an overflow of its resistance at a tensile strain of 12.5%. On the other hand, the Au film, which was formed with a 150-nm-thick parylene F layer, revealed an much improved resistance characteristics: $1.21{\Omega}$ as its initial resistance and $246{\Omega}$ at its 30% elongation state. With swelling of PDMS substrate, the resistance of an Au film substantially decreased to $14.4{\Omega}$ at 30% tensile strain.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.04a
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• pp.69-73
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• 1997

Microwave Plasma assisted CVD (Chemical Vapor Deposition) and DC Plasma CVD were used to prepare thin and thick diamond film, respectively. Diamond coated silicon nitride and fiee standing diamond thick film were eroded by silicon carbide particles. The velocity of the solid particle was about 220m/sec. Phase transformation and the other crack formation were investigated by using Raman spectroscopy and microscopy.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.1
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• pp.117-123
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• 2014

The fabrication and characterization of a Si/ZnO thin film heterojunction ultraviolet photodiode has been presented in this paper. ZnO thin film of ~100 nm thick was deposited on <100> Silicon (Si) wafer by atomic layer deposition (ALD) technique. The Photoluminescence spectroscopy confirms that as-deposited ZnO thin film has excellent visible-blind UV response with almost no defects in the visible region. The room temperature current-voltage characteristics of the n-ZnO thin film/p-Si photodiodes are measured under an UV illumination of $650{\mu}W$ at 365 nm in the applied voltage range of ${\pm}2V$. The current-voltage characteristics demonstrate an excellent UV photoresponse of the device in its reverse bias operation with a contrast ratio of ~ 1115 and responsivity of ~0.075 A/W at 2 V reverse bias voltage.