organization of nanowire arrays for integrated nanosystems presenter: octavian florescu
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Organization of Nanowire Arrays for Integrated Nanosystems Presenter: Octavian Florescu Authors: Lieber group Department of Chemistry and Chemical Biology, Harvard University. Organization of nanowires Why is it important? Criteria for organization Methodology Results Conclusions. - PowerPoint PPT PresentationTRANSCRIPT
Organization of Nanowire Arrays for Integrated Nanosystems
Presenter: Octavian Florescu
Authors: Lieber group
Department of Chemistry and Chemical Biology, Harvard University
Outline
• Organization of nanowires– Why is it important?– Criteria for organization
• Methodology• Results• Conclusions
Organizing Nanowires
• Why?– Critical to the realization of integrated electronics, photonics and
sensors• Criteria for organization
– Controllability– Yield– Reproducibility– Reliability– Cost
Controlled 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 silane
Cui et al., APPL. PHYS. LETT VOL. 78, NO 15
Deposition 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, 1255-1259
Deposition 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, 1255-1259
Finer 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, 951-954
Finer Deposition Results
• 90nm pitch was produced with 40nm linewidth
• Control of both pitch and linewidth– In this case pitch
independent of LB compression
Whang et al., NANO LETTERS 2003, Vol. 3, No. 9, 951-954
Integration with Electronics
a) Electrodes with same pitch as SiNW align well with the nanowires
b) PL used to pattern active areas containing SiNW
Electrodes deposited over SiNW active areas
Jin et al., NANO LETTERS, 2004, Vol. 4, No. 5
915-919
Realization
• 80% of the 3000 electrodes are bridged by SiNWs
• Can be combined with NIL, EUV to generate very dense arrays of electrodes
Whang et al., NANO LETTERS 2003, Vol. 3, No. 9, 951-954
Electrical Performance
• gm = 1250nA/V• Ion/Ioff = 107
• Ssubthreshold = 160mV/decade• μ = 307cm2/V*s
Whang et al., NANO LETTERS 2003, Vol. 3, No. 9, 951-954
Another Realization
• Size of FET depends on the spacing between SiNWs, which depends on the LB compression.
• Decent control of VTH
Whang et al., NANO LETTERS 2003, Vol. 3, No. 9, 951-954
Conclusions• 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 you!