• Journal of Sensor Science and Technology
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• v.29 no.6
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• pp.394-398
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• 2020

In this paper, we report the sensing performance of H₂ gas sensors composed of Pd/carbon nanotube (CNT) buckypaper at room temperature. The CNT buckypaper was made using a simple filtration process and subsequently deposited with Pd as the sensing material. The sensitivity of the sensor increased with respect to the gas concentration. To investigate the effect of Pd thickness, Pd layers of different thickness were deposited on the buckypaper, and the response of the sensor was evaluated. The proposed sensor exhibits excellent sensing properties with optimized Pd thickness at room temperature (25℃). Pd nanoparticles significantly impact the sensitivity and selectivity of the sensor because of the spillover effect. In addition, the sensor is highly suitable for bendable and wearable devices owing to its structural flexibility.

• Korean Journal of Optics and Photonics
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• v.18 no.6
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• pp.389-394
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• 2007

The characteristics of the single mode fiber hydrogen sensor have been investigated theoretically and experimentally. Palladium is adopted as a material for the transducer and a thin Ni film is used for the adhesion between the fiber end and the Pd film. It is shown that sensitivity and response time strongly depend on the thickness of Pd film. The single mode fiber sensor coated with 5 nm thick Ni adhesion layer and 10 nm thick Pd transducer layer showed 0.6 dB change of reflectivity and $3{\sim}5$ sec of response time as it absorbed 4% hydrogen gas.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.104-106
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• 2004

GIS의 금속으로 차폐된 폐쇄형 스페이서(barrier)의 에폭시 주입구를 통해 방사되는 극초단파 부분방전 신호를 검출할 수 있는 외장형 UHF PD 센서를 제작하였다. 센서에 내장되는 패치안테나는 모노폴(monopole)과 다이폴(dipole) 형태로 설계하여 고주파 전자기장 해석 툴을 이용하여 각각의 특성을 계산하고 분석하였다. 제작된 센서는 362kV GIS의 차폐형 스페이서의 에폭시 주입구에 장착하고 각 센서의 PD 검출 감도와 주파수 특성을 측정하고 비교하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.160-161
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• 2008

$SnO_2$는 n형 반도체로써 3.6 eV의 큰 밴드갭을 가지는 물질로 CO와 NOx 가스에 좋은 감도를 나타내는 것으로 보고되고 있다. 문헌에 따른 일반적인 $SnO_2$ 가스센서는 후막이나 벌크형태로 제작되었다. 근래에는 가스감응체가 $SnO_2$ 나노선 형태인 가스센서가 활발한 연구 중에 있다. 본 논문에서는 기판 위에 서로 분리된 전극 패턴에 Au를 촉매로 하여 네트워크 구조로 된 $SnO_2$ 나노선이 합성되었다. 제작된 가스센서에 Pd 도핑에 따른 영향을 알아보기 위하여 1.8 mM의 Pd 용액 ($PdCl_2{\cdot}xH_2O$ 3 mg + $H_2O$ 10 ml)을 이용하여 센서에 도핑하였다. 측정 시스템에서 $NO_2$ 가스에 대한 센서의 특성을 분석한 결과 도핑하지 않은 $SnO_2$ 센서보다 20%정도의 감도가 개선되었다.

• Journal of Sensor Science and Technology
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• v.18 no.3
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• pp.222-225
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• 2009

This paper describes the fabrication and characteristics of Schottky micro hydrogen sensors for high temperatures by using polycrystalline(poly) 3C-SiC thin films grown on Si substrates with thermal oxide layer using APCVD. Pd/poly 3C-SiC Schottky diodes were made and evaluated by I-V and C-V measurements. Electric current density and barrier height voltage were $2{\times}10^{-3}A/cm^2$ and 0.58 eV, respectively. These devices could operate stably at about 400 $^{\circ}$. The characteristics of implemented sensors have been investigated in terms of sensitivity, linearity of response, response rate, and response time. Therefore, from these results, Pd/poly 3C-SiC Schottky devices have very high potential for high temperature $H_2$ sensor applications.

• Journal of Sensor Science and Technology
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• v.20 no.5
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• pp.289-293
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• 2011

Networked $SnO_2$ nanowires were uniformly functionalized with Pd nanoparticles via ${\gamma}$-ray radiolysis. The Networked $SnO_2$ nanowires were fabricated through a selective growth method. The sensing properties of the Pd-functionalized $SnO_2$ nanowires were analyzed in terms of their response to $NO_2$ and CO gases. The response time and sensitivity of the sensors were significantly improved for $NO_2$ at lower temperatures by the Pd functionalization. The enhancement in the sensing properties is likely to be due to the spillover effect of the Pd nanoparticles.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.711-714
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• 2002

촉매 구조에 따른 반도체식 가스센서의 가스 감지 특성이 고찰되었다. 촉매로는 Pd를 사용하였고, 0.5 ~ 10wt% 의 다양한 농도로 약 15nm 크기의 $SnO_2$ 분말에 도핑, 가스센서를 제작하였다. 또한 열처리 온도를 $500{\sim}600^{\circ}C$로 다르게 하여 각 촉매 구조에 따른 특성의 변화를 관찰하였다. 그 결과 가스 감지 특성은 열처리 온도가 높을수록 감지 특성이 향상되었고, Pd 농도가 5wt% 에서 감도가 0.65로 좋은 감지 특성을 나타내었다. 5wt% Pd가 도핑된 가스센서는 2시간 동안 $400^{\circ}C$에서 aging 후에도 감도 값이 안정된 우수한 특성을 나타내었다.

• Transactions on Semiconductor Engineering
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• v.1 no.1
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• pp.9-13
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• 2023

An AlGaN/GaN heterojunction-based hydrogen sensor with SnO₂ nanoparticles/Pd catalyst layer was fabricated for room-temperature hydrogen detection. The fabricated sensor exhibited unstable drift in standby current when it was operated at room temperature. The instability in the sensing signal was dramatically improved when the sensor was operated under UV illumination.

• Journal of Energy Engineering
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• v.19 no.1
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• pp.21-24
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• 2010

We present a novel electrochemical method to fabricate a single Pd nanowire based on direct current assisted dielectropheresis (DEP) process between two predefined metal electrodes. The electrochemical methods was investigated as functions of frequency and voltage for optimal growth conditions of Pd nanowire. The synthesized Pd nanowire have a good resistance of $1\;k{\Omega}$, diameters of several hundred nanometers on average and lengths of $8\;{\mu}m$. Finally, the single Pd nanowire was capable of detecting hydrogen in the concentration range from 100 to 2500 ppm with high sensitivity and response time, thus demonstrating its suitability for use as a hydrogen sensor.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2197-2202
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• 2014

In this paper, we report on an investigation of highly sensitive sensing performance of a hydrogen sensor composed of palladium (Pd) nanowires. The Pd nanowires have been grown by electrodeposition into nanochannels and liberated from the anodic aluminum oxide (AAO) template by dissolving in an aqueous solution of NaOH. A combination of photo-lithography, electron beam lithography and a lift-off process has been utilized to fabricate the sensor using the Pd nanowire. The hydrogen concentrations for 2% and 0.1% were obtained from the sensitivities (${\Delta}R/R$) for 1.92% and 0.18%, respectively. The resistance of the Pd nanowires depends on absorption and desorption of hydrogen. Therefore, we expect that the Pd nanowires can be applicable for detecting highly sensitive hydrogen gas at room temperature.