• 한국결정성장학회지
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• 제10권4호
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• pp.309-317
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• 2000

Langasite is a promising new piezoelectric material for SAW filter application. Little was known until recently about the methods needed to mechanically polish and chemically polish/etch this material. In this experiment, polishing, slurry chemistry and chemical wet etching for langasite is described. Conventional quartz and LN ($LiNbO_3$) polishing methods did not produce satisfactory polished surfaces, and polishing with a colloidal silica slurries has shown to be most effective. The optimum condition was investigated by changing the slurry chemistry. As the planarization effect is very important in SAW filter applications, the examination of the effective particle number effect and the particle size effect was carried out. Z-cut langasite surface which had been polished with the colloidal silica slurries was etched in a variety of etchants. Conventional quartz etchants destroyed the polished surface. Other etchants formed a thin film on the surfaces. In this experiment, the reaction between langasite and a few etching solution was analysed. And an appropriate selective etchant solution for analyzing the defects was synthesized.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.48-48
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• 2011

We have developed a chemically-driven top-down approach using vapor phase HCl to form various GaN nanostructures and successfully demonstrated dislocation-free and strain-relaxed GaN nanostructures without etching damage formed by a selective dissociation method. Our approach overcomes many limitations encountered in previous approaches. There is no need to make a pattern, complicated process, and expensive equipment, but it produces a high-quality nanostructure over a large area at low cost. As far as we know, this is the first time that various types of high-quality GaN nanostructures, such as dot, cone, and rod, could be formed by a chemical method without the use of a mask or pattern, especially on the Ga-polar GaN. It is well known that the Ga-polar GaN is difficult to etch by the common chemical wet etching method because of the chemical stability of GaN. Our chemically driven GaN nanostructures show excellent structure and optical properties. The formed nanostructure had various facets depending on the etching conditions and showed a high crystal quality due to the removal of defects, such as dislocations. These structure properties derived excellent optical performance of the GaN nanostructure. The GaN nanostructure had increased internal and external quantum efficiency due to increased light extraction, reduced strain, and improved crystal quality. The chemically driven GaN nanostructure shows promise in applications such as efficient light-emitting diodes, field emitters, and sensors.

• 전자공학회논문지A
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• 제33A권7호
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• pp.149-155
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• 1996

A new technique wasdeveloped which obtains selectively the htick fully recessed oxidized porous silicon layer (OPSL) with good dielectric property. The porous silicon layer was ocnverted to thick fully recessed oxide (FRO) with 3-step (1${\mu}$m, 1.5${\mu}$m, 1.8${\mu}$m) by multi-step thermal oxidation (after 400$^{\circ}$C, 1 hour by dry oxidation, 700$^{\circ}$C, 1 hour and then 1100$^{\circ}$C, 1 hour by wet oxidation). The breakdwon field of the FRO was about 2.5MV/cm and the leakage current was several pA ~ 100 pA in the range of 0 of 90 pF. The progress of oxidation of a porous silicon layer was studied by examining the infrared abosrption spectra. The refractive index (1.51) of the fRO, which was measured by ellipsometer, was comparable to that of the thermally grown silicon dioxide (1.46). The etching rate (1600${\AA}$/min) of the FRO was also almost equal to that of the thermal oxide.

• 센서학회지
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• 제7권1호
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• pp.73-82
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• 1998

실리콘 표면 미세가공에 있어서, 새로 개발된 HF 기상식각 공정은 미소구조체들을 띄우는데 매우 효과적임을 입증하였다. 무수 불화수소와 메탄올을 이용한 기상식각 시스템에 대한 기능 및 특성을 기술하였고, 실리콘 미세구조체룰 띄우기 위한 회생층 산화막들의 선택적 식각특성이 고찰되었다. 구조체층으로는 인이 주입된 다결정실리콘이나 SOI 기판의 단결정실리콘을 사용하였다. 회생층으로는 TEOS 산화막, 열산화막, 저온산화막을 사용하였다. 기존 습식식각과 비교해 볼 때, 공정에 기인된 고착현강이나 잔류물질이 없는 미세구조체를 성공적으로 제작하였다.

• 한국정밀공학회지
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• 제30권1호
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• pp.128-133
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• 2013

Si Nanowire (Si-NW) arrays were fabricated by top-down method. A relatively simple method is suggested to fabricate suspended silicon nanowire arrays. This method allows for the production of suspended silicon nanowire arrays using anisotropic wet etching and conventional MEMS method of SOI (Silicon-On-Insulator) wafer. The dimensions of the fabricated nanowire arrays with the proposed method were evaluated and their effects on the Field Effect Transistor (FET) characteristics were discussed. Current-voltage (I-V) characteristics of the device with nanowire arrays were measured using a probe station and a semiconductor analyzer. The electrical properties of the device were characterized through leakage current, dielectric property, and threshold voltage. The results implied that the electrical characteristics of the fabricated device show the potential of being ion-selective field effect transistors (ISFETs) sensors.

• 태양에너지
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• 제17권4호
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• pp.3-11
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• 1997

다결정 실리콘에서 결정입계는 광생성된 반송자들의 재결합 중심으로 작용할 뿐 아니라 전위장벽으로 작용하여 태양전지의 변환효율을 감소시킨다. 결정입계의 영향을 줄이기 위해 열처리, 결정입계에 대한 선택적 식각, 결정입계로 함몰전극을 형성하는 방법, 다양한 전극 구조, 초박막 금속 형성 후 전극형성 등 여러가지 요소들을 조사하였다. 질소 분위기에서 $900^{\circ}C$ 전열처리, $POCl_3$ 확산을 통한 게터링, 후면전계 형성을 위한 Al 처리로 다결정 실리콘의 결함밀도를 감소시켰다. 결정입계에서의 반송자 손실을 감소시키기 위한 기판 처리로 Schimmel 식각액을 사용하였다. 이는 texturing 효과와 함께 결정입계를 선택적으로 $10{\mu}m$ 깊이로 식각하였다. 결점입계를 우선적으로 식각한 후면으로 Al을 확산하여 후면에서의 재결합 손실을 감소시켰다. 전극 핑거(grid finger) 간격이 0.4mm인 세밀한 전극 구조에 결정입계로 $0.4{\mu}m$ 깊이로 함몰전극을 추가로 형성하여 태양전지의 단락 전류 밀도가 개선되었다. 80% 이상의 광투과율을 보인 20nm 두께의 크롬 박막 형성으로 직렬 저항을 감소시켰다. 본 논문은 저가의 고효율, 지상 전력용 태양진지를 위해 결정입계에 대한 연구를 하였다.