• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.364-364
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• 2009

The solar cell is in the spotlight as a future green energy source. In the solar cells based on silicon wafer, the improvement of efficiency is one of crucial issues. One of techniques for high efficiency is texturing on the surface of solar cells. We studied the laser texturing on the surface of multi-crystalline silicon solar cells. The laser texturing followed by chemical etching is adequate for the multi-crystalline structure which have random crystallographic directions. We used the fiber laser for texturing and the SiNx as a masking layer for etching process. We investigated the shapes of holes for texturing in the various laser power conditions and analyzed the holes after removal of thermal damages caused by laser ablation through a 3D profiler.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.2
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• pp.114-119
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• 2000

Etch characteristics of SF6/CI2 electron cyclotron resonance (ECR) plasmas have been investigated. Surface reaction of gas plasma with polysilicon was also analysed using X-ray photoelectron spectroscopy (XPS). At the same time, the relationship between surface reaction and the etched profile of polysilicon was examined using XPS. The etch rate of polysilicon and oxide increases with increasing flow rate of SF6 in the SF6/CI2 gas mixture, and tis selectivity also increase also increase. It was also found that as increasing flow rate of SF6 in the SF6/CI2 gas mixture, the atomic% of chlorine detected at surface region decrease, but F and S contents increase. At the same time, when the mixing ratio of SF6 gas increases, the anisotropy of etched polysilicon is sharply decreased in the 0%~10% range of the SF6 mixing ratio, but is rarely varied in the range over 10%, in spite of the large variations in flow rates. It can be explained that the bonding of S-Si due to SiSx(x$\leq$2) compound formed on the etched surface suppress the formation of Si-Cl and 'or Si-F bonding in the silicon etching.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.9
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• pp.1020-1025
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• 2012

In this study, we fabricated the superhydrophobic and super-water-repellent surface with the micro/nano scale structures using simple conventional silicon wet-etching technique and the black silicon method by deep reactive ion etching. These fabrication methods are simple but very effective. Also we reported the droplet impact experimental results on the micro/nano-scaled surface. There are two representative impact behaviors as "rebound" and "fragmentation". We found the transition Weber number between "rebound" and "fragmentation" statements, experimentally. Additionally, we concerned about the dimensionless spreading diameters for our super-water-repellent surface. The novel characterization method was introduced for analysis including the "fragmentation" region. As a result, our super-water-repellent surface with the micro/nano-scaled structures shows the different impact behaviors compared with a reference smooth surface, by some meaningful experiments.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.274-277
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• 1991

A piezoresistive silicon resonator which can be used as an accelerometer is designed and fabricated using silicon micromachining techniques. The device consists of a seismic mass and four deflection beams in which eight piezoresistors are diffused. The structure is fabricated by EPW etching process. The piezoresistors are properly arranged and connected to make a bridge circuit, with which acceleration in only one direction can be measured. According to the experimental results, the first resonant frequency of this resonator is above 15 kHz, and this transducer has a sensitivity of 5.56 ${\mu}V/Vg$.

• Journal of Sensor Science and Technology
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• v.3 no.1
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• pp.19-25
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• 1994

When etching rectangular convex corners of silicon using anisotropic etchants such as KOH, deformation of the edges always occurs due to undercutting. Therefore, it is necessary to correct the mass pattern for compensation. Experiments for the compensation method to prevent this phenomenon were carried out. In the result, the compensation pattern of a regular square is suitable for acceleration sensors considering space. With this consequence, silicon piezoresistive acceleration sensor with compensated square pillar type of mass has been fabricated using SDB wafer.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.3
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• pp.299-305
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• 1995

Visible photoluminescing (PL) silicon at room temperature has been prepared by a dry technique, that is, by spark processing, contrary to anodically etched porous silicon. PL peak maximum of photoluminescing spark processed Si was shifted to blue 520 nm. The stability of spark processed Si towards degradation upon UV radiation was found to be extremely high. Results from high resolution TEM, XRD and XPS studies suggest that spark processed silicon involves minute nanocrystalline (polycrystalline) particles which are imbedded in an amorphous matrix, preferably $SiO_2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.17-20
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• 1998

Thermal behavior of Flow Pattern Defect (FPD) and Large Pit (LP) in Czochralski Silicon crystals was investigated by applying high temperature ($\geq$1100$^{\circ}C$) annealing and non-agitation Secco etching. For evaluation of the effect of LP upon device performance / yield, DRAM and ASIC devices were fabricated. The results indicate that high temperature annealing generates LPs whereas it decreases FPD density drastically, and LP does not have detrimental effects on the performance /

• Journal of the Optical Society of Korea
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• v.20 no.2
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• pp.291-299
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• 2016

We have investigated the ultimate limits of nonuniform grating couplers (NGCs) for optimized fiber coupling to silicon waveguides, compared to uniform grating couplers (UGCs). Simple grating coupler schemes, which can be fabricated in etching steps of the conventional complementary metal-oxide semiconductor (CMOS) process on silicon-on-insulator (SOI) wafers without forming any additional overlay structure, have been simulated numerically and demonstrated experimentally. Optimum values of the grating period, fill factor, and groove number for ultimate coupling efficiency of the NGCs are determined from finite-difference time-domain (FDTD) simulation, and confirmed with experimentally demonstrated devices by comparison to those for the UGCs. Our simulated results indicate that maximum coupling efficiency of NGCs is possible when the minimum pattern size is below 50 nm, but the experimental value for the maximum coupling efficiency is limited by the attainable fabrication tolerance in a practical device process.

• Transactions on Electrical and Electronic Materials
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• v.1 no.1
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• pp.6-11
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• 2000

The hydrogen plasma treatment of silicon wafers in the reactive ion-etching mode was studied for the application to silicon-on-insulator wafers which were prepared using the wafer bonding technique. The chemical reactions of hydrogen plasma with surface were used for both surface activation and removal of surface contaminants. As a result of exposure of silicon wafers to the plasma, an active oxide layer was found on the surface. This layer was rendered hydrophilic. The surface roughness and morphology were examined as functions of the plasma exposing time and power. In addition, the surface became smoother with the shorter plasma exposing time and power. The value of initial surface energy estimated by the crack propagation method was 506 mJ/㎡, which was up to about three times higher as compared to the case of conventional direct using the wet RCA cleaning method.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2004.11a
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• pp.3-4
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• 2004

A flexible Packaging scheme, which embedded chip packaging, has been developed using a thinned silicon chip. Mechanical characteristics of thinned silicon chips are examined by bending test and finite element analysis. Thinned silicon chips ($t<50{\mu}m$) are fabricated by chemical etching process to avoid possible surface damages on them. These technologies can be use for a real-time monitoring of blood pressure. Our research targets are implantable blood pressure sensor and its telemetric measurement. By winding round the coronary arteries, we can measure the blood pressure by capacitance variation of blood vessel.