• Title/Summary/Keyword: Pd film

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The effect of initial Pd catalyst oxidation stale on CH$_4$sensitivity of SnO$_2$thin film sensor (Pd 촉매의 부분 산화 조절을 이용한 SnO$_2$박막 센서의 CH$_4$감도 변화 연구)

  • Choi, W. K.;Cho, J.;Cho, J. S.;Song, J. H.;Jung, H. J.;Koh, S. K.
    • Journal of the Microelectronics and Packaging Society
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    • v.6 no.2
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    • pp.45-49
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    • 1999
  • A flammable gas sensor based on the $SnO_2$thin film deposited by the reactive ion assisted deposition was fabricated and ultra-thin Pd layer as catalyst was adsorbed at surface by ion beam sputtering. The initial oxidation states of Pd catalyst were controlled to investigate the role of Pd in the sensing process of inflammale gas sensor through annealing in air and vacuum respectively. The Pd catalyst existing in pure metallic state showed the sensitivity higher than that of PdO. The result might be closely related to the fact that PdO as a surface acceptor would receive electrons via Pd sub-channel from $SnO_2$, and thus which reduces the sensitivity and delay the response time.

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Hydrogen Absorption Kinetics on Al/Pd Film in the $\alpha$ Phase (Al/Pd 박막의 수소 흡수 동역학[$\alpha$상])

  • Cho, Young-Sin
    • Transactions of the Korean hydrogen and new energy society
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    • v.18 no.3
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    • pp.334-341
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    • 2007
  • Al film(135.5 nm thick) with Pd film(39.6 nm thick) was made by thermal evaporation method. Electrical resistance change by hydrogen absorption and desorption was measured with four point measurement method. Even though Al film(135.5 nm thick) did not absorb any hydrogen at room temperature, Al/Pd film absorbed hydrogen at upto 640 torr pressure. Hydrogen absorption kinetics was monitored by measuring resistance change of the sample in the temperature range from $25^{\circ}C$ to $40^{\circ}C$. Absorption activation energy of Al/Pd film was about 10.7 and 17.7 kcal/mol H for 1st stage and last stage respectively at 1 torr hydrogen pressure. This activation values are bigger than that of Pd film, but are much less than that of Al film. This result indicates there is possibility that Al can be storage material for hydrogen by using Pd film evaporation on it.

Effect of Plasma Etching and $PdCl_2/SnCl_2$ Catalyzation on the Performance of Electroless Plated Copper Layer (플라즈마 에칭 및 $PdCl_2/SnCl_2$ 촉매조건이 무전해 동도금 피막의 성능에 미치는 영향)

  • 오경화;김동준;김성훈
    • Journal of the Korean Society of Clothing and Textiles
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    • v.27 no.7
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    • pp.843-850
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    • 2003
  • Cu/PET film composites were prepared by electroless copper plating method. In order to improve adhesion between electroless plated Cu layer and polyester (PET) film, the effect of pretreatment conditions such as etching method, mixed catalyst composition were investigated. Chemical etching and plasma treatment increased surface roughness in decreasing order of Ar>HCl>O$_2$>NH$_3$. However, adhesion of Cu layer on PET film increased in the following order: $O_2$<Ar<HCl<NH$_3$. It indicated that appropriate surface roughness and introduction of affinitive functional group with Pd were key factors of improving adhesion of Cu layer. PET film was more finely etched by HCI tolution, resulting in an improvement in adhesion between Cu layer and PET film. Plasma treatment with NH$_3$produced nitrogen atoms on PET film, which enhances chemisorption of Pd$^{2+}$ on PET film, resulting in improved adhesion and shielding effectiveness of Cu layer deposited on the Pd catalyzed surface. Surface morphology of Cu plated PET film revealed that Pd/Sn colloidal particles became more evenly distributed in the smaller size by increasing the molar ratio of PdCl$_2$; SnCl$_2$from 1 : 4 to 1 : 16. With increasing the molar ratio of mixed catalyst, adhesion and shielding effectiveness of Cu plated PET film were increased.d.

The Hydrogen Gas Sensing Characteristics of the Pd-doped $SnO_2$ Thin Films Prepared by Sputtering (스퍼터링법으로 제조된 Pd-doped $SnO_2$ 박막의 수소가스 감도 특성)

  • 차경현;김영우;박희찬;김광호
    • Journal of the Korean Ceramic Society
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    • v.30 no.9
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    • pp.701-708
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    • 1993
  • Pd-doped SnO2 thin films for hydrogen gas sensing were fabricated by reactive fo magnetron sputtering and were studied on effects of film thickness and Pd doping content. Pd doping caused the optimum sensor operation temperature to reduce down to ~25$0^{\circ}C$ and also enhanced gas sensitivity, compared with undoped SnO2 film. Gas sensitivity depended on the film thickness. The sensitivity increased with decreasing the film thickness, showing maximum sensitivities at the thickness of 730$\AA$ and 300~400$\AA$ for the undoped SnO2 and the Pd-doped SnO2 film, respectively. Further decrease of the film thickness beyond these thickness ranges, however, resulted in the reduction of sensitivity again.

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Hydrogen Absorption Characteristics of Al/Pd Film (Al/Pd 박막의 수소 흡수 특성)

  • Cho, Young-Sin
    • Transactions of the Korean hydrogen and new energy society
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    • v.17 no.2
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    • pp.234-240
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    • 2006
  • Al film(135.5 nm thick) with Pd film(39.6 nm thick) on the top of it was made by thermal evaporation method. Hydrogen absorption of Al/Pd film was measured by quartz crystal microbalance(QCM) method at room temperature. The sample was activated by hydrogen absorption and desorption cycling at room temperature. Hydrogen was introduced into the film by increasing hydrogen gas pressure step by step up to 640 torr at room temperature. Hydrogen concentration reached up to 25% at $5{\sim}10$ torr. But at high pressure the concentration decreased. This strange tendency was not understood yet. Further study is needed to find out the mechanism of hydrogen absorption in Al in Al/Pd film.

Magnetism of Pd(111) Thin Films: A First-principles Calculation (Pd(111) 박막의 자성: 제일원리계산)

  • Hong, Soon Cheol
    • Journal of the Korean Magnetics Society
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    • v.26 no.1
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    • pp.1-6
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    • 2016
  • Pd has the highest magnetic susceptibility among single element metals and often shows ferromagnetism under some special environments. In this paper, we report magnetism of 5- and 9-monolayers (ML) calculated by using full-potential linearized augmented plane wave method. Exchange-correlation interaction is taken into account in local density approximation (LDA) and generalized gradient approximation (GGA) and calculational results in LDA and GGA are compared with each other. It is found that calculations by LDA are more reliable compared to those by GGA because LDA prediction of paramagnetism of bulk Pd is consistent with experiments, whereas GGA predicts wrongly ferromagnetim of bulk Pd. Calculational results in LDA on a 5-ML Pd(111) thin film shows a ferromagnetic ground state unlike a paramagnetic ground state of bulk Pd. The center Pd layer of the 5-ML Pd(111) thin film has the largest magnetic moment ($0.273{\mu}_B$) among the layers and |m| = 1 orbital states play a dominant role in stabilizing the ferromagnetism of the 5-ML Pd(111) thin film. A 9-ML Pd(111) thin film in a ferromagnetic state has almost the same total energy as in a paramagnetic state. Since the magnetization of the 9-ML Pd(111) thin film is stable, the ferromagnetic state may be meta-stable.

Study of Pd Target Power Effects on Physical Characteristics of Pd-Doped Carbon Thin Films Using Dual Magnetron Sputtering Method (듀얼 마그네트론 스퍼터링 법으로 제조된 Pd-Doped Carbon 박막의 물리적 특성에서 Pd 타겟 전력의 영향에 대한 연구)

  • Choi, Young-Chul;Park, Yong Seob
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.35 no.5
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    • pp.488-493
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    • 2022
  • Generally, diamond-like carbon films (a-C:H, DLC) have been shown to have a low coefficient of friction, a high hardness and a low wear rate. Pd-doped C thin film was fabricated using a dual magnetron sputtering with two targets of graphite and palladium. Graphite target RF power was fixed and palladium target RF power was varied. The structural, physical, and surface properties of the deposited thin film were investigated, and the correlation among these properties was examined. The doping ratio of Pd increased as the RF power increased, and the surface roughness of the thin film decreased somewhat as the RF power increased. In addition, the hardness value of the thin film increased, and the adhesive strength was improved. It was confirmed that the value of the contact angle indicating the surface energy increases as the RF power increases. It was concluded that the increase in RF power contributed to the improvement of the physical properties of Pd-doped C thin film.

Magnetic Properties of High Electrical Resistive CoPdAlO Film for RF Device (높은 비저항을 갖는 RF 소자용 CoPdAlO 박막의 자기적 특성)

  • 김택수;이영우;김종오
    • Journal of the Korean Magnetics Society
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    • v.11 no.3
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    • pp.109-113
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    • 2001
  • Presently, an inductor adapted at MMIC (Monolithic Microwave Integrated Circuit) which is used for cellular phone or PHS operates at quasi-microwave range over 800 MHz. However, a W-CDMA (Wideband Code Division Multiple Access) will use about 2 GHz range. Therefore magnetic film device should be compatible up to 2 GHz. We have deposited Co-Pd-Al-O system film using rf sputtering method which is expected up to 2 GHz, and investigated the effect of Pd content and magnetic field annealing. When Pd composition is 19%, Hk was 118 Oe, and ${\mu}$′showed flat frequency characteristics up to 1.5 GHz. The Q factor (=${\mu}$′/${\mu}$") was 23.3 at 1 GHz, 6.7 at 1.5 GHz and 1.5 at 2 GHz, respectively. Resonance frequency was 2 GHz. Therefore Co-Pd-Al-O thin film could be used at over 1 GHz, and also expected as an inductor material for wide band CDMA type cellular phone.

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Change of Electrical Resistivity of PdH film as a Function of Film Thickness (수소흡수시 Pd 박막 시료의 두께 변화에 따른 전기저항의 변화)

  • Cho, Young-sin
    • Transactions of the Korean hydrogen and new energy society
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    • v.10 no.3
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    • pp.171-175
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    • 1999
  • Pd films($180{\sim}670{\AA}$ thick) were made by thermal evaporation. Electrical resistance of the films was measured during hydrogen absorption-desorption process at room temperature. Resistance changes as a function of hydrogen pressure in thin films of the PdH system show a strong dependence on film thickness. $({\Delta}R_{\infty}/R_0)_{{\beta}min}$ for a $\670{\AA}$ film is 0.61. For a $\180{\AA}$ film, this is 0.34. Resistance change also depends on sample preparation condition.

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Optical Transmittance Change of Pd Thin Film by Hydrogen Absorption and Desorption (수소 흡수-방출에 의한 Pd 박막의 광투과도 특성변화)

  • Cho, Young sin
    • Transactions of the Korean hydrogen and new energy society
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    • v.12 no.4
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    • pp.287-292
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    • 2001
  • The optical transmittance change of Pd thin film due to hydrogen absorption and desorption was examined at room temperature. Hydrogen absorption and desorption cycling effects on optical transmittance were measured 6 times in the pressure range between 0 and 640 torr. Optical transmittance of Pd film was increasing with increasing hydrogen pressure. Ratio of optical transmittance to the change of pressure at $\beta$ phase is bigger than that of low hydrogen pressure range.

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