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Sub ppm Gas Sensing Using a CNTFET-Based Sensor Array Fabricated Using Dierent Metals as Electrodes
Paolo Bondavalli,Pierre Legagneux,Didier Pribat 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.1
This paper deals with the fabrication of carbon nanotube eld effect transistors (CNTFETs) for gas sensing applications. The aim of this study is to achieve a sort of fingerprinting of a specific gas by using an array of CNTFET-based sensors. The electronic ngerprinting will be obtained by exploiting the change of the metal electrode work function after gas exposure. This one strictly depends on the metal/gas interaction and consequently in uences univocally the transfer characteristics of each transistors. To demonstrate this original concept, we have fabricated different CNTFETs using different metal contacts: Au, Pt and Mo. Using these transistors, we have shown that a specific gas, in our case DiMethyl-Methyl-Phosphonate (DMMP, a sarin simulant), interacts specifically with each metal: exposure to 0.5 ppm of DMMP reduces the transistor ON current by 10 %, 60 % and 25 % after 5 minutes respectively for Au, Pt, Mo-based CNTFETs at V<SUB>GS</SUB> = -25 Volt. We think that this new approach can be applied for highly selective sensing of various gases using ultra-compact, room temperature and very low power devices. This paper deals with the fabrication of carbon nanotube eld effect transistors (CNTFETs) for gas sensing applications. The aim of this study is to achieve a sort of fingerprinting of a specific gas by using an array of CNTFET-based sensors. The electronic ngerprinting will be obtained by exploiting the change of the metal electrode work function after gas exposure. This one strictly depends on the metal/gas interaction and consequently in uences univocally the transfer characteristics of each transistors. To demonstrate this original concept, we have fabricated different CNTFETs using different metal contacts: Au, Pt and Mo. Using these transistors, we have shown that a specific gas, in our case DiMethyl-Methyl-Phosphonate (DMMP, a sarin simulant), interacts specifically with each metal: exposure to 0.5 ppm of DMMP reduces the transistor ON current by 10 %, 60 % and 25 % after 5 minutes respectively for Au, Pt, Mo-based CNTFETs at V<SUB>GS</SUB> = -25 Volt. We think that this new approach can be applied for highly selective sensing of various gases using ultra-compact, room temperature and very low power devices.
Alumina-coated silicon-based nanowire arrays for high quality Li-ion battery anodes
Nguyen, Hung Tran,Zamfir, Mihai Robert,Duong, Loc Dinh,Lee, Young Hee,Bondavalli, Paolo,Pribat, Didier The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.47
<P>Amongst other requirements, a good anode for Li-ion battery applications must exhibit dimensional stability upon Li insertion, as well as chemical inertness with respect to the electrolyte. This latter characteristic is usually provided by the so-called solid electrolyte interphase (SEI), a passivating film that is formed at the end of the first lithiation step, originating from the partial reduction of the electrolyte and Li salt. However, silicon, which exhibits the highest known capacity for Li alloying, possesses none of the above attributes when used as an anode material. Actually, the large volume expansion of Si upon alloying with Li induces a mechanical instability of the SEI film, which therefore fails to provide its protective role. In this paper, we have studied the effect of thin alumina deposits on top of Si-based nanowires. A thin alumina deposit will act as a substitute for the SEI, preventing electrolyte decomposition. We observe that even if alumina films crack during lithiation–delithiation steps of the Si-based nanowires, they still provide some kind of protection, prolonging the lifetime of the anode. Using Al<SUB>2</SUB>O<SUB>3</SUB>-coated Si-based nanowires, we have been able to obtain a lifetime of 1280 cycles when the capacity of the anode was limited to 1200 mA h g<SUP>−1</SUP>. We also show that uncoated Si nanowires degrade more rapidly when cycled under identical conditions.</P> <P>Graphic Abstract</P><P>We have studied the effect of thin Al<SUB>2</SUB>O<SUB>3</SUB> coatings on Si-based nanowires for Li-ion battery anodes. We report a lifetime of 1280 cycles when the capacity is limited to 1200 mA h g<SUP>−1</SUP>. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm35125k'> </P>