변위센서응용을 위한 피라미드형 실리콘 턴널링소자의 제조

마대영(Tae Young Ma),박기철(Ki Cheol Park),김정규(Jeong Gyoo Kim) 한국센서학회 2000 센서학회지 Vol.9 No.3

N/A The tunneling current is exponentially dependent on the separation gap between a pair of conductors. The detection of displacement can be, therefore, carried out by measurement of a variation in the tunneling current. In this experiment, we fabricated pyramid-type silicon tunneling devices in which a tunneling current flow between a micro-tip and Si₃N₄ thin film membrane. A MEMS process was used for the fabrication of the tunneling devices. The micro-tips were formed on Si wafers by undercutting a differently oriented square of SiO₂ with KOH. The stiffness of the Si₃N₄ films were observed and the model for the stiffness calculation, which is useful in predicting the stiffness even when the stiffness ranges beyond the scone of the normal experimental condition, was suggested.

초음파 분무법으로 제조한 a-Fe2O3막의 구조적 및 전기적 특성에 미치는 기판온도 효과

마대영,김정규 한국센서학회 2004 센서학회지 Vol.13 No.4

a-Fe2O3 films were prepared by ultrasonic spray pyrolysis (USP) on SiO2 coated Si wafers using iron acetylacetonateas an iron precursor. The crystallographic properties and surface morphologies of the films were characterized by X-raydifraction (XRD) and scanning electron microscopy (SEM), respectively. X-ray photoelectron spectroscopy (XPS) wascarried out to determine the Fe oxidation states. In order to observe stability of the films to temperature, the resistancevariation of the films with an ambient temperature was measured. The effects of substrate temperature on the structuraland electrical properties of the a-Fe2O3 films were studied. The films were densified from the substrate temperature of350oC. The grain size of the films grown at 400oC was shown to be increased abruptly comparing with that of 350oC.The films showed a low resistance variation between the ambient temperature of 300oC and 350oC.

LaCoO3 후막의 가스 감지 특성

박기철,마대영,신정호,김정규,장재영 한국센서학회 1999 센서학회지 Vol.8 No.6

LaCoO₃ thick-films for gas sensing layers were prepared on alumina substrate by screen printing method. The sensitivities to C₄H_(10), NH₃, NO and CO gases were investigated for different heat treatment temperatures of the films. Their structural properties were examined by X-Ray Diffraction measurements and SEM photographs. The sensitivity of LaCoO₃ thick-film to CO gas was much higher than those of C₄H_(10). NH₃ and NO gases. The optimal heat treatment and operating temperatures were 800 ℃ and 150 ℃, respectively. The sensitivities of LaCoO₃ thick-films to 500ppm and 1250ppm CO gas were 72% and 95%, respectively.

AI₂O₃를 첨가한 LaFeO₃후막의 암모니아 가스 감지특성

박기철,마대영,김정규,김준곤,안병렬 한국센서학회 2002 센서학회지 Vol.11 No.1

LaFe03-based thick films with 2wt. %, 5wt. % and 10wt. % A1₂O₃ additives were fabricated by screen printing method on A1₂O₃ substrates. Structural, electrical and ammonia gas sensing characteristics of the thick films with different heat treatment temperatures were examined. From XRD results, the compound of LaFeO₃ and A1₂O₃ was not found until the heat treatment at 1200℃. SEM microphotograph showed similar grain growth despite the amount of A1₂O₃ additives with the heat treatment. Thick films with high activation energy and low resistance in the electrical properties showed high sensitivity for gases. Thick films with 2wt.% A1₂O₃ additives heat-treated at 1200℃ showed the sensitivities of 210% for 100 ppm N₃ gas at the working temperature, of 350℃. The thick films showed good selectivity to NH₃ gas.

드레인오프셋트 다결정실리콘 박막트랜지스터의 누설전력 해석

이인찬,김정규,마대영 한국전기전자재료학회 2001 전기전자재료학회논문지 Vol.14 No.2

Poly-Si TFT's(Polysilicon thin filmtransistors) have been actively studied due to their applications in active matrix liquid crystal displays and active pull-up devices of CMOS SRAM's. For such applications, the leakage current has to be in the range of sub-picoampere. However, poly-Si TFT's suffer from anomalous high leakage currents, which is attributed to the emission of the traps present at gain boundaries in the drain junction. The leakage current has been analyzed by the field emission via grain-boundary traps and thermionic field emission over potential barrier located at the grain boundary. We found that the models proposed before are not consistent with the experimental results at far as drain-offset poly-Si TFT's we fabricated concern. In this paper, leakage current of drain-offset poly-Si TFT's with different offset lengths was studied. A conduction model based on the thermionic emission of the tunneling electrons is developed to identify the leakage mechanism. It was found that the effective grain size of the drain-offset region is important factor in the leakage current. A good agreement between experimental and simulated results of the leakage current is obtained.

후막 철산화물의 가스감지 특성

조철형,이복상,마대영,박기철,김정규 경상대학교 생산기술연구소 2003 工學硏究院論文集 Vol.19 No.-

Fe₂O₃ thick films with 6% glassy bond(Bi₂O₃65%, B₂O₃13%, PbO11%. SiO₂10%, Sb₂O₃l%)were fabricated by screen printing method on Al₂O₃ substrates. Electrical, structural and gas sensing characteristics of the thick films with heat treatments at 700℃, 800℃, 900℃ were examined. The resistivity of thick films decreased with increasing heat treatment temperature and (110), (320) Fe₂O₃ crystalline planes growth was observed. Thick films heat-treated at 800℃ showed highest sensitivity for CO, NH₃, C₄H_(8), NO gases. Especially, the sensitivity was about 33% for l00ppm CO gas at the working temperature of 250 C. Though sensitivity was not high enough for above gases, thick films heat-treated at 800 C showed good selectivity to NO and NH₃ gases. The response time was several tens of second.

Al₂O₃를 첨가한 LaFeO₃ 후막의 암모니아 가스 감지특성

김준곤,안병렬,마대영,박기철,김정규,Kim, Jun-Gon,Ahn, Byeong-Yeol,Ma, Tae-Young,Park, Ki-Cheol,Kim, Jeong-Gyoo 한국센서학회 2002 센서학회지 Vol.11 No.1

스크린 프린팅법으로 $Al_2O_3$ 기판 위에 $LaFeO_3$를 기본물질로 하여 $Al_2O_3$를 각각 2Wt.%, 5wt.%, 10wt.%를 첨가한 후막을 제조하였다. 열처리 온도에 따른 후막의 구조적, 전기적 특성과 암모니아 가스에 대한 감지특성을 조사하였다. X선 회절에서, 첨가한 $Al_2O_3$는 $1200^{\circ}C$까지의 열처리에도 $LaFeO_3$와 반응하여 화합물을 형성하지 않음을 확인하였다. 전자현미경 사진에서 $Al_2O_3$의 첨가량에 따른 열처리에 대한 입자의 변화는 차이를 보이지 않았다. 후만의 전기적 특성에서 활성화 에너지가 높고 전기저항이 작은 시료에서 가스감도가 좋았다. $Al_2O_3$를 2wt.% 첨가하여 $1200^{\circ}C$에서 열처리한 후막은 100ppm $NH_3$ 가스에 대해 동작온도 $350^{\circ}C$에서 210%의 감도를 보였다. 이 후막은 $NH_3$ 가스에 대해 우수한 선택성을 보였다. $LaFeO_3$-based thick films with 2wt.%, 5wt.% and 10wt.% $Al_2O_3$ additives were fabricated by screen printing method on $Al_2O_3$ substrates. Structural, electrical and ammonia gas sensing characteristics of the thick films with different heat treatment temperatures were examined. From XRD results, the compound of $LaFeO_3$ and $Al_2O_3$ was not found until the heat treatment at $1200^{\circ}C$. SEM microphotograph showed similar grain growth despite the amount of $Al_2O_3$ additives with the heat treatment. Thick films with high activation energy and low resistance in the electrical properties showed high sensitivity for gases. Thick films with 2wt % $Al_2O_3$ additives heat-treated at $1200^{\circ}C$ showed the sensitivities of 210% for 100 ppm $NH_3$ gas at the working temperature of $350^{\circ}C$. The thick films showed food selectivity to $NH_3$ gas.

관형 알루미나 정밀여과와 광촉매 코팅 폴리프로필렌 구의 혼성 수처리: 질소 역세척 주기와 시간의 영향

박진용,최민지,마정규 한국막학회 2013 멤브레인 Vol.23 No.3

The effect of N2 back-flushing period (FT) and time (BT) was compared with the previous result used PES (polyethersulfone) beads loaded with titanium dioxide photocatalyst in hybrid process of alumina microfiltration and PP (polypropylene) beads coated with photocatalyst in viewpoints of membrane fouling resistance (Rf), permeate flux (J), and total permeate volume (VT). The reason of nitrogen back-washing instead of the general air back-washing method is to minimize the possible effect of oxygen included in air on water quality analysis. As decreasing FT, Rf decreased and J and VT increased. Treatment efficiency of dissolved organic matters (DOM) was 82.0%, which was the higher than 78.0% of the PES beads result. This means that PP beads coated with photocatalyst was the more effective than PES beads loaded with photocatalyst in the DOM removal. As increasing BT, the final Rf decreased and the final J increased, but VT was the maximum at BT 15 sec. The average treatment efficiency of turbidity did not have any trend as changing BT. As BT increasing from 6 sec to 30 sec, the treatment efficiency of DOM increased 11.8%, which was a little higher than the result of PES beads. 관형 알루미나 정밀여과와 이산화티타늄 광촉매 코팅 PP (polypropylene) 구의 혼성공정에서 질소 역세척 주기 (FT)와 시간(BT)의 영향을 막오염에 의한 저항(Rf) 및 투과선속(J), 총여과부피(VT)의 관점에서 광촉매 첨가 PES (polyethersulfone) 구를 사용한 기존 결과와 비교하였다. 일반적인 역세척 방법인 공기가 아닌 질소로 역세척을 한 이유는 공기에 포함 된 산소에 의해 수질분석에 영향을 줄 가능성을 최소화하기 위한 것이다. FT가 짧아질수록 Rf는 감소하고, J와 VT는 증가하 였다. 용존유기물의 평균 처리효율은 82.0%로 PES 구 결과의 78.0% 보다 높았다. 이러한 결과는 광촉매 코팅 PP 구가 광촉 매 첨가 PES 구 보다 효과적으로 용존유기물을 제거한다는 것을 의미한다. BT가 길어질수록 최종 Rf는 감소하고 최종 J는 증가하였지만, VT는 BT 15초에서 최대값을 보였다. 탁도의 평균 처리효율은 BT 변화에 따라 특별한 경향을 보이지 않았다. BT가 6초에서 30초로 증가함에 따라 용존유기물의 처리효율은 11.8% 증가하여, PES 구의 결과보다 다소 크게 증가하였다.

Al2O3를 첨가한 LaFeO3 후막의 암모니아 가스 감지특성

김준곤,안병렬,마대영,박기철,김정규 한국센서학회 2002 센서학회지 Vol.11 No.1

스크린 프린팅법으로 Al2O3 기판 위에 LaFeO3를 기본물질로 하여 Al2O3를 각각 2wt.%, 5wt.%, 10wt.%를 첨가한 후막을 제조하였다. 열처리 온도에 따른 후막의 구조적, 전기적 특성과 암모니아 가스에 대한 감지특성을 조사하였다. X선 회절에서, 첨가한 Al2O3는 1200oC까지의 열처리에도 LaFeO3와 반응하여 화합물을 형성하지 않음을 확인하였다. 전자현미경 사진에서 Al2O3의 첨가량에 따른 열처리에 대한 입자의 변화는 차이를 보이지 않았다. 후막의 전기적 특성에서 활성화 에너지가 높고 전기저항이 작은 시료에서 가스감도가 좋았다. Al2O3를 2wt.% 첨가하여 1200℃에서 열처리한 후막은 100ppm NH3 가스에 대해 동작온도 350℃에서 210%의 감도를 보였다. 이 후막은 NH3 가스에 대해 우수한 선택성을 보였다. LaFeO3-based thick films with 2wt.%, 5wt.% and 10wt.% Al2O3 additives were fabricated by screen printing method on Al2O3 substrates. Structural, electrical and ammonia gas sensing characteristics of the thick films with different heat treatment temperatures were examined. From XRD results, the compound of LaFeO3 and Al2O3 was not found until the heat treatment at 1200oC. SEM microphotograph showed similar grain growth despite the amount of Al2O3 additives with the heat treatment. Thick films with high activation energy and low resistance in the electrical properties showed high sensitivity for gases. Thick films with 2wt.% Al2O3 additives heat-treated at 1200℃ showed the sensitivities of 210% for 100 ppm NH3 gas at the working temperature of 350℃. The thick films showed good selectivity to NH3 gas.

AZO투명도전막의 전기적 및 광학적 특성

이형기,심호섭,마대영,김정규,박기철 慶尙大學校 工科大學 自動化및컴퓨터應用技術硏究所 1995 自動化 및 컴퓨터應用技術 Vol.2 No.1

Highly conductive and transparent films have been fabricated by RF magnetron sputtering from the ZnO targets mixed with Al₂O₃ranging from 0wt.% to 5wt.%. And electrical and optical properties of them have been investigated as functions of deposition conditions. Hall effect and optical transmittance measurements showed that the optimized AZO films 1500Å thick had the resistivity of 4.7×10^-4Ω·㎝, the Hall mobility of 15㎠/V·sec and the carrier concentration of 8×10^20/㎤ and the optical transmittance more than 90% at 550nm. The optical band gap from optical transmittance of pure ZnO and AZO film deposited from the target with 3wt.% Al₂O₃3.3eV and 3.53eV, respectively. This values are comparable to those for ITO(In₂O₃: Sn) and FTO(SnO₂: F) transparent conductive films presently used as a transparent electrode.