000204218 001__ 204218
000204218 005__ 20190509132517.0
000204218 0247_ $$2doi$$a10.5075/epfl-thesis-6468
000204218 02470 $$2urn$$aurn:nbn:ch:bel-epfl-thesis6468-7
000204218 02471 $$2nebis$$a10339866
000204218 037__ $$aTHESIS
000204218 041__ $$aeng
000204218 088__ $$a6468
000204218 245__ $$aTri-gate silicon nanowire transistors for ultra-low pH resolution and improved scalability
000204218 269__ $$a2014
000204218 260__ $$bEPFL$$c2014$$aLausanne
000204218 336__ $$aTheses
000204218 502__ $$aProf. A. Kis (président) ; Prof. C. Guiducci (directrice) ; Dr T. Ernst,  Prof. M. Reed,  Prof. Ph. Renaud (rapporteurs)
000204218 520__ $$aThe scalability of on-chip analytical systems based on field-effect transistors as pH sensors is limited by the degradation of the signal to noise ratio when decreasing the device size. Nano-sized tri-gate transistors such as silicon nanowires and nanoribbons exhibit improved coupling with the electrolyte environment thanks to their tri dimensional structure. Even though in the framework of solid-state tri-dimensional transistors an enhancement of the channel con-ductivity is achieved by reducing the device width, so far the sensitivity performance of liquid-gate devices has been mostly considered in terms of threshold voltage readout. In pH sensing applications, however, the threshold voltage change is independent on the device size, thus overlooking the potential advantage derived from the improved electrical properties of nano sized devices. In this thesis, sensitivity characterization coupled with a comprehensive noise analysis has been performed on devices ranging from 50 nm to 70 µm in width and from 350 nm to 4250 nm in length. Such comprehensive characterization is made possible thanks to the employement indus-trial top down CMOS compatible technology, which ensures high control over process variation and enables the fabrication of nanowires with a wide range of widths and lengths. The results show that reducing the width below few hundreds of nanometers results in an increase of the conductivity properties of silicon nanoribbons, which ultimately improves the sensitivity with respect to surface charge, hence to pH. This enhanced sensitivity of nanoscaled devices can be further exploited within a multi wire configuration, in which the exposed surface is increased and the noise reduced. We provide experimental evidence that multi wire devices maximize the signal to noise ratio achieving, in the presented technology, a resolution of 0.0028 pH·µm2. This result could have a great impact on the improvement of the scalability of on-chip analytical systems requiring high pH resolution, such as DNA sequencing and quantitative PCR.
000204218 6531_ $$aISFET
000204218 6531_ $$asilicon nanowires
000204218 6531_ $$asilicon nanoribbons
000204218 6531_ $$atri gate
000204218 6531_ $$asurface-to-volume ratio
000204218 6531_ $$apH sensitivity
000204218 6531_ $$a1/f noise
000204218 6531_ $$amulti fingers
000204218 6531_ $$aquantitative PCR
000204218 6531_ $$asmall molecules detection
000204218 700__ $$0243943$$g188024$$aAccastelli, Enrico
000204218 720_2 $$aGuiducci, Carlotta$$edir.$$g190693$$0243928
000204218 8564_ $$uhttps://infoscience.epfl.ch/record/204218/files/EPFL_TH6468.pdf$$zn/a$$s38085538$$yn/a
000204218 909C0 $$xU12017$$0252239$$pCLSE
000204218 909CO $$pthesis$$pthesis-bn2018$$pDOI$$ooai:infoscience.tind.io:204218$$qDOI2$$qGLOBAL_SET$$pSTI
000204218 917Z8 $$x108898
000204218 917Z8 $$x108898
000204218 917Z8 $$x108898
000204218 917Z8 $$x108898
000204218 917Z8 $$x108898
000204218 917Z8 $$x108898
000204218 918__ $$dEDMI$$cIBI-STI$$aSTI
000204218 919__ $$aCLSE
000204218 920__ $$b2015$$a2015-1-23
000204218 970__ $$a6468/THESES
000204218 973__ $$sPUBLISHED$$aEPFL
000204218 980__ $$aTHESIS