Slide 1OutlineOrganizing NanowiresControlled Growth of NanowiresDeposition of Nanowire Arrays on SubstrateDeposition ResultsFiner Deposition …Finer Deposition ResultsIntegration with ElectronicsRealizationElectrical PerformanceAnother RealizationConclusionsThank you!Organization of Nanowire Arrays for Integrated NanosystemsPresenter: Octavian FlorescuAuthors: Lieber groupDepartment of Chemistry and Chemical Biology, Harvard UniversityOutline•Organization of nanowires–Why is it important?–Criteria for organization•Methodology•Results•ConclusionsOrganizing Nanowires•Why?–Critical to the realization of integrated electronics, photonics and sensors•Criteria for organization–Controllability–Yield–Reproducibility–Reliability–CostControlled Growth of Nanowires•p or n-SiNW with good diameter distribution were grown by VLS–Substrate was oxidized silicon–Catalyst was Au nanoparticls–Reactant was silaneCui et al., APPL. PHYS. LETT VOL. 78, NO 15Deposition of Nanowire Arrays on Substratea) SiNW are suspended using a surfactant in nonpolar solvent. Compressed in a Langmuir-Blodgett trough. Compression determines center to center spacing.b) SiNW transferred onto Si substrate.Whang et al., NANO LETTERS 2003, Vol. 3, No. 9, 1255-1259Deposition Results•200nm to 2um pitch realizable •Decent control of the periodicity and wire width•Can cover over 20cm2 in area.Whang et al., NANO LETTERS 2003, Vol. 3, No. 9, 1255-1259Finer Deposition …•In this scenario SiNW are coated with a sacrificial layer and are compressed until they touch.•Can be used as a mask for deposition of metal NW.Whang et al., NANO LETTERS 2003, Vol. 3, No. 9, 951-954Finer Deposition Results•90nm pitch was produced with 40nm linewidth •Control of both pitch and linewidth–In this case pitch independent of LB compressionWhang et al., NANO LETTERS 2003, Vol. 3, No. 9, 951-954Integration with Electronicsa) Electrodes with same pitch as SiNW align well with the nanowiresb) PL used to pattern active areas containing SiNW Electrodes deposited over SiNW active areasJin et al., NANO LETTERS, 2004, Vol. 4, No. 5915-919Realization•80% of the 3000 electrodes are bridged by SiNWs •Can be combined with NIL, EUV to generate very dense arrays of electrodesWhang et al., NANO LETTERS 2003, Vol. 3, No. 9, 951-954Electrical Performance•gm = 1250nA/V•Ion/Ioff = 107•Ssubthreshold = 160mV/decade•μ = 307cm2/V*sWhang et al., NANO LETTERS 2003, Vol. 3, No. 9, 951-954Another Realization•Size of FET depends on the spacing between SiNWs, which depends on the LB compression.•Decent control of VTHWhang et al., NANO LETTERS 2003, Vol. 3, No. 9, 951-954Conclusions•Good–80% device yield–Inexpensive–Reproducible (?)•Bad–Low gain•Unknown–Controllability of device characteristics–Reliability•Not suitable yet for ICs but can be interesting for use in thin film electronics and as transducers.Thank
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