저전력형 부탄가스 감지소자의 제조 및 그 특성

강봉휘,이덕동,임준우,장경훈 경북대학교 전자기술연구소 1996 電子技術硏究誌 Vol.17 No.1

Low power consuming butane gas sensors were fabricated using mica substrate which is a thin and elastic insulator. To increase the sensitivity and the stability, various catalyst layers were formed on SnO₂ thin layer. Among them, SnO₂/Pt(17Å)/Pd(30Å) and SnO₂/Pt(8Å)/Pd(30Å) thin layer showed good characteristics in stability and dependence of temperature and humidity. The size of fabricated sensors was 1×3 ㎟ and the consumed power was lower than 100 ㎽ at operating temperature(250℃). For 2,000 ppm butane concentration, the response time and the recovery time was about 5 seconds and 15 seconds respectively. The sensitivity of the sensors was about 80% for 5,000 ppm butane concentration.

금속 산화물 나노구조형 마이크로 박막 센서의 제작 및 가스 응답 특성

강봉휘,이덕동,이상록,송갑득,주병수 대한전자공학회 2006 電子工學會論文誌-SD (Semiconductor and devices) Vol.43 No.8

SnO2 and ZnO nanostructures were grown on the surface of thin film by heat treatment of metal Sn, Zn under Ar gas flow and O2 at atmospheric pressure, respectively. The sensitivity of the SnO2 thin film device on which grown nanowires to CO gas(5,000 ppm) was 50 % at the operating temperature of 200 ℃. In case of using Pt as catalysts, the sensitivity was enhanced and operating temperature was reduced(73 % at 150 ℃). The sensitivity of the ZnO nanorods device using Cu as catalysts to NOX gas was 90 % at the operating temperature of 200 ℃. It was found that the sensitivity to CO and NOX gases for the device on which grown nanostructures was much higher than those for general thin film device. Sn과 Zn 금속을 이용해 각각 산소와 아르곤 가스를 주입한 대기압 분위기에서 열처리를 통해 SnO2와 ZnO 나노박막을 형성시켰다. 나노구조로 형성된 SnO2 박막의 경우 CO 가스(5,000 ppm)에 대해 200 ℃의 동작온도에서 약 50 %의 감도를 나타내었으며, SnO2 나노 금속산화물에 Pt 금속을 이온 코팅법에 의해 첨가한 박막의 경우에는 동작온도 150 ℃에서 73 %의 높은 감도를 얻을 수 있었다. 순수 ZnO 나노 박막의 경우 NOx(20 ppm) 가스에 대해 낮은 감도를 나타내었으나, Cu를 이온 코팅법에 의해 첨가한 박막의 경우에는 동작온도 200 ℃에서 90 %의 높은 감도를 나타내었다. 나노 구조가 아닌 SnO2와 ZnO 박막이 가지는 CO와 NOx에 대한 가스 감도에 비해 매우 높은 감도를 가짐을 알 수 있었다.

SnO_2 열산화감지막의 제작 및 특성

강봉휘,이덕동 한국센서학회 2002 센서학회지 Vol.11 No.6

본 논문에서는 새로운 방식의 금속 산화물 감지막의 형성 기술에 대해서 제안을 하였다. Sn 증착을 위해 사용된 기판은 Pt 전극을 가진 실리콘 웨이퍼를 이용하였다. 증착 방식은 금속 Sn이 연속적인 막이 아닌 island로만 형성된 상태로 하였다. 제안된 방식의 최적의 Sn 증착 조건을 구하기 위해 Pt 전극간의 저항이 1 kΩ, 5 kΩ, 10 kΩ 및 50 kΩ이 되도록 Sn을 증착하여 시료를 제작하였다. 또한 일반적인 방식과 새롭게 제안된 방식의 시료를 비교하기 위해서 Sn 막의 두께가 1,500 Å인 시료를 준비하였다. 이것들을 700℃의 산소분위기에서 3시간 동안 산화를 하여 SnO_2를 형성하였다. 산화물 감지막들의 특성 평가를 위해서 SEM, XRD 및 AFM을 이용하였다. 분석을 통하여 10kΩ의 시료(300 Å)가 최적의 감지막 증착 조건임을 알았다. 또한 제조된 감지막을 다양한 농도의 부탄, 프로판 및 일산화탄소에 대해서 동작온도 250 ℃, 300 ℃ 및 350 ℃ 의 경우에 대해서 측정하였다. 그 결과 촉매를 첨가하지 않았음에도 불구하고 모든 가스에 대한 높은 감도 특성을 나타내었다. New formation technique of metal of oxide sensing film was proposed in this paper. Silicon wafer with Pt electrodes was used as a substrate for depositing metal Sn film. Metal Sn was deposited in the state of not continuous film but only island state. The samples were prepared to obtain the optimal condition of metal Sn deposition. The resistances of deposited Sn onto Pt electrodes amounted to 1 kΩ, 5 kΩ, 10 kΩ and 50 kΩ, respectively. Also The sample with 1,500 Å thickness of Sn was prepared in order to compare sensing properties between conventional type and proposing type. After deposition of metal Sn, SnO_2 was formed by thermal oxidation method for 3 hrs. in O_2 ambient at 700℃. Surface morphology, crystal structure and surface roughness of oxidized-sensing film were examined by SEM, XRD, and AFM, respectively. From the results of these analyses, the optimal deposition condition of Sn was that the Pt electrode resistance became 10 kΩ (300 Å). Also, the sensing characteristics of fabricated sensing film for various concentrations of butane, propane and carbon monoxide gases were measured at the operating temperatures of 250 ℃, 300 ℃ and 350 ℃, respectively. Although catalyst was not added to the sensing film, it has exhibited the high sensitivity to all the test gases.

졸-겔법을 이용한 In2O3 박막의 오존 센서

강봉휘,이덕동,최낙진,송갑득,이윤수,주병수 한국센서학회 2001 센서학회지 Vol.10 No.2

A highly selective, sensitive and reliable ozone sensing In₂O₃ thin film was fabricated by a sol-gel method. The fabricated film is operated at a relatively lower temperature than ever developed thin films and saved operating power. In₂O₃ films deposited by sol-gel technique has been recently attracted because it is an economical and energy saving method and precisely controlled microstructure. Indium alkoxide precursor was synthesized from the reaction between indium hydroxide and butanol. PVA binder was used to improve adhesion of the films. The In₂O₃ thin films were obtained by spin citing from 1 to 5 times followed by drying at 100℃ and calcining at 600℃ for 1h. The film thickness was controlled by the number of coating time. The morphology and the thickness of the In₂O₃ films were examined by a SEM and XRD. The In₂O₃ thin films show a high sensitive to ozone gas at operating temperature of 250℃. The In₂O₃ sensor has very good selectivity to CH₄, CO, C₄H_(10) and ethanol.

Micro-Gas Sensor

임준우,강봉휘,정완영,이덕동 대한전자공학회 1997 대한전자공학회 학술대회 Vol.1997 No.1

온도 구배를 갖는 마이크로 가스센서 어레이의 제작 및 그 특성

이대식,강봉휘,이덕동,정완영,심창현,임준우,정호용 경북대학교 전자기술연구소 2001 電子技術硏究誌 Vol.22 No.1

A micro gas sensor array was fabricated by anodic bonding of the thin and insulating membrane of 125 ㎛-thick coming 7740 glass and the already-micromachined silicon substrate, as a supporter of the membrane. On the insulating membrane, two sensing films of SnO₂ and SnO₂+Pt sensing films on six pairs of electrodes, respectively, located symmetrically from the center part were deposited. The heating temperature-controlled method as an operating mode of sensor array was proposed to obtain the diverse sensing patterns. By controlling the temperature of a heater to the two steps of 450℃ and 200℃, 24 sensitivity patterns were obtained. From principal component analysis results, we confirmed that the classifying ability of the sensor array was enhanced by adding the 12 sensing signals obtained by controlling the heating temperature.

결정성장 억제재를 첨가한 SnO$_{2}$ 미세입자의 메탄가스 감지효과

홍영호,강봉휘,이덕동 한국전기전자재료학회 1996 電氣電子材料學會誌 Vol.9 No.1

A coprecipitation method was used for preparing Ca and Pt doped $SnO_2$ fine powder. Components of the powder were investigated by XPS and SIMS. Crystallite size and specific surface area were investigated by TEM, XRD, and BET analysis. $SnO_2$(Ca)/Pt based thick film devices were prepared by a screen printing technique for methane gas detection. Then sensing characteristics of the devices were investigated. As Ca and Pt added, the crystal growth of $SnO_2$ was suppressed during calcining and sintering, and the sensitivity of $SnO_2$(Ca)/Pt thick film to methane gas was enhanced. For the Pt doped $SnO_2$ fine particle, the thick film device shows sensitivity of about 83% to 2000 ppm methane gas at an operating temperature of >$400^{\circ}C$.

Sc₂O₃를 첨가한 SnO₂/Ca,Pt 가스센서의 부탄감응 특성

이윤수,성정훈,강봉휘,서무교,이덕동 경북대학교 센서기술연구소 1997 센서技術學術大會論文集 Vol.8 No.1

A coprecipitation method was used for preparing Ca and Pt doped SnO_(2) powder. Components were investigated by XRD and SEM. Sc_(2)O_(3) added SnO_(2) /Ca,Pt thick film devices were fabricated by screen printing technique for butane gas detecting. By addition of Sc_(2)O_(3), the selectivity of SnO_(2) /Ca,Pt thick film for butane gas was enhanced. The sensitivity of Sc_(2)O_(3) added SnO_(2) /Ca,Pt device to 3,000 ppm butane in air was about 90% at the operating temperature. of 200℃. And the device showed good selectivity for butane gas.

적외선 센서를 이용한 다종가스 계측기 구현

최낙진,류정호,강봉휘,이광우,이덕동 경북대학교 센서기술연구소 1997 센서技術學術大會論文集 Vol.8 No.1

The semiconductor gas sensors with a tin oxide as the raw material have been generally used to detect gases in the principle of electrical conductivity variation. However, it was difficult to design the gas detection system due to the non-selectivity, the non-stability and the influence of temperature, humidity etc. Therefore, it was proposed NDIR(non-dispersive infrared) method using pyroelectric infrared sensor to overcome the disadvantage of the semiconductor gas sensors. This method has been recently used to detect various gases in industrial parts. It has the advantages of selectivity, stability and responsibility. The gases used in this paper were CO_(2)(carbon dioxide) and HC(hydrocarbon) series. The system was designed with the Intel MCU i8097BH microprocessor. Main topics were to remove interference effect for other gases and to minimize influence for ambient circumstance by using the software and the hardware techniques.

저전력형 부탄가스 감지소자의 제조 및 그 특성

장경훈,임준우,강봉휘,이덕동 경북대학교 센서기술연구소 1995 센서技術學術大會論文集 Vol.6 No.1

Low power consuming butane gas sensors were fabricated using mica substrate which is a thin and elastic insulator. To increase the sensitivity and the stability, various catalyst layers were formed on SnO_(2) thin layer. Among them, SnO_(2) /Pt(17Å)/Pd(30Å) and SnO_(2) /Pt(8Å )/Pd(30Å) thin layer showed good characteristics in stability and dependance of temperature and humidity. The size of fabricated sensors was 1 x 3 mm^(2) and the consumed power was lower than 100 mW at operating temperature(250℃). For 2000 ppm butane concentration, the response time and the recovery time were about 5 seconds and 15 seconds respectively. The sensitivity of the sensors was about 80 % for 5000 ppm butane concentration.