may-oct 2003 review – optical properties of nanoscale arrays, cmi-001; fabricate voltage-tunable...

May-Oct 2003 Review – Optical Properties of Nanoscale Arrays, CMI-001;

Fabricate Voltage-Tunable Photonic Devices Filled With Ferroelectrics, P/097

CMI Project Review:

Optical Properties of Nanoscale Arrays

CMI-001

Fabricate Voltage-Tunable Photonic Devices

Filled with Ferroelectrics

P/097

April-Oct 2003



Optical Properties of Nanoscale ArraysVoltage-Tunable Photonic Devices

Cambridge PI : Prof. James F. Scott, Earth Science Dept.

MIT PI : Prof. Keith A Nelson, Chemistry Dept.• Brief Description of Project:

Fabricate micron- or submicron-arrays of voltage-tunable ferroelectric devices consisting of two-dimensional patterns of high refractive index rods

Characterize GHz-THz dielectric responses through "polaritonics" measurements w/ micron spatial resolution

• Summary of Intended Outcomes:

Delivery and test of a small number of prototype devices

Prototype apparatus for GHz-THz dielectric metrology




Ferroelectric nanotube arrays fabricated by the Cambridge group




International interest in nanotube arrays




"Polaritonics" platform developed by the MIT groupGHz-THz signal generation, guidance, control, focusing, imaging, & readout

Spatiotemporal imaging allows direct visualization of wave

propagation

Spatiotemporal femtosecond pulse shaping sends pulses to specified addresses at specified times to launch polariton waves

Femtosecond laser machining of polariton waveguides, tips, & other functional elements




Polaritonics: The Movies

Polaritons Fabricated Structures

Coherent Control



Progress In Past Six Months

• Important activities, collaborations:Successfully filled arrays 5 mm x 5 mm in size with ferroelectric nano-tubes as

small as 800 nm in outside diameter; this is an array of ca. 2500 x 2500 = 5 million nanotubes

Collaboration with M. Alexe et al. at Max Planck Institute for Microstructural Physics, Halle, Germany, and A. Sigov et al., Moscow Technical University, Russia (reported in invited review Reviews in Advanced Materials Science 4, pp.114-122 (2003))

Interfaced new femtosecond laser system (acquired with CMI support) to homebuilt and homedesigned femtosecond pulse shaping appartus

Measured GHz-THz complex dielectric responses of ferroelectric materials (without fine spatial resolution) - found high ' with sufficiently low ", indicating possibility for extremely fine polariton focusing, high throughput, high intensity

Conducted 3D finite difference time domain (FDTD) simulations of GHz-THz polaritons with Beowulf computational cluster (acquired with CMI support)



Progress In Past Six Months

• Milestones achieved:Reproducibe deposition via “mist” chemical solution deposition (CSD) of 40-nm

wall-thickness ferroelectric nanotubes of strontium bismuth tantalate (SBT)Both nanotubes embedded in Si and free-standing arrays (attached only at one

end) reliably producedDemonstration of spatiotemporal femtosecond pulse shaping method that

permits single light pulse to be directed to selected location with selected time-dependent waveform

• Deliverables completed:One porous Si sample with ca. 5 million nanotubes of SBT (embedded – not

free-standing)Publication: Automated spatiotemporal diffraction of ultrashort pulses, J.C.

Vaughan, T. Feurer, and K.A. Nelson, Optics Letters, in press.



Plans For Next Six Months

• Expected activities, collaborations :• New deposition technique (simplified) using fluid pore-wetting rather

than misted CSD

• Use of cheap, commercially available porous alumina rather than porous Si

• Deposition of palladium electrodes

• Characterization of additional ferroelectric materials GHz-THz dielectric functions for selection of optimal tip components

• Generation of high-intensity GHz-THz polaritons for potential applications in ultrafast noncontact switching of ferroelectrics

• FDTD simulations of tips to optimize geometry, composition

• Preliminary attempts at tip fabrication



Plans For Next Six Months

• Expected milestones:• Achievement (never reported by other laboratories) of concentric

cylindrical electrodes using organic Pd precursors

• Measurement of voltage-tunable effects

• 10-50 kV/cm polariton field levels reached for attempts at FE switching

• Expected deliverables:• One to five electrodes prototype devices

• Disclosure and patent filing for GHz-THz scanning microscopy tips and methods

• Publication of FDTD simulations of GHz-THz polaritons



Other Items

• Developments worth publicizing:• Rather exciting and unplanned discoveries have occurred: We recognized

that the nanotube arrays we produce exceed the state-of-the-art wall thickness uniformity and aspect ratio for trenched dielectric capacitors in silicon DRAMs (dynamic random access memories). Therefore patents have been filed on this discovery and application. Our very recent publication of such prototype device structures (J. Phys. Condensed Matter , 15, L527-532 (2003)) was immediately picked up by Japanese industry press (attached article from Nikkan Kogyo Shimbun, 20 August).

• A second, perhaps equally important, application of these devices (since they are hollow piezoelectric tubes) is for ultra-precise ink-jet print heads. By the usual cross-tie row-and-column addressing, these permit a 5 mega-pixel page-at-a-time ink-jet printing with no rastering of the head.

• "Polaritonics" platform for GHz-THz wave generation, guidance, control, focusing, visualization, and readout, with applications in signal processing & metrology



Other Items

• Modifications to statement of work and/or funding:• Because of the unexpected developments above, we suggest

that the work statement be modified to permit further exploration of these unexpected applications of our nanotube arrays. The potential financial impact for trenched Si DRAMs is very large and has already been recognized in Japan. The possible application to ink-jet printer arrays is facilitated by the proximity in Cambridge of the Epson-Cambridge Laboratory (Seiko-Epson), with which we have close contact.

• However, we emphasize that these new opportunities should not impair the timely production of the photonic prototypes originally specified as deliverables.



Other Items

• Modifications to statement of work and/or funding:• Because of the high polariton field levels achievable and the unique

focusing prospects in high-dielectric ferroelectrics, exploration of optically controlled, ultrafast switching of nanoscale ferroelectrics should be undertaken. This is a completely novel prospect with potential ultrahigh-bandwidth signal processing applications.

• These new opportunities should complement, not impair, the originally planned development of polariton-based GHz-THz metrology methods.

• CMI support should be maintained or increased through the duration of the CMI project, with following main objectives:

• Nanoscale FE fabrication taken to exportable, practical stage

• New applications brought to commercial development stage

• Exportable prototype GHz-THz metrology instrument demonstrated



Other Items

• Expected financial profile:• We believe that several Japanese corporations would be

interested in buying IP at this stage. We have already had discussions with Samco International Corp. in Kyoto (a medium-sized equipment manufacturer for the semiconductor industry) about this.

• Anything else:• PI Scott will be delivering two plenary invited talks on this new

breakthrough this summer (European Physical Society Meeting, Prague, July; and International Symposium on Ferroelectric Domains, Tsukuba, August). These are good marketing opportunities for Europe and Asia.

• PI Nelson will be delivering invited talks and organizing leading ultrafast spectroscopy meeting in Japan this summer, with good opportunities for highlighting CMI project.



Challenges And/or Issues To Address

• Problem/Concern:• We need to find an inexpensive commercial source of highly

registered photonic silicon substrates. Our German supplier is no longer producing. The Si substrates are more perfectly ordered arrays than are the available alumina.

• We need help in marketing the DRAM trench intellectual property. Suggested market: Infineon/Toshiba; Fujitsu; Matsushita; or Samsung.

• MIT effort is now highly labor-intensive, with progress in materials characterization, tip design & fabrication, simulation, study of samples from Cambridge, generation of high polariton amplitudes, exploration of polariton-based FE switching, and construction of scanning metrology instrument all requiring intense effort and some equipment.



Challenges And/or Issues To Address

• Plan for resolution:• If Si source is not located, we will limit prototypes to Al2O3.• Some degree of piggybacking on other polaritonics projects at

MIT can provide help in materials characterization, high polariton amplitudes, and exploration of FE switching. However, all work on Cambridge samples, on simulation and fabrication of polaritonic tips, on measurements with micron spatial resolution, and on development of scanning metrology instrument are supported by CMI alone.

• How CMI can help:• MIT may have local or own source of buying/making porous Si?• CMI could help with active marketing of the DRAM trenching IP.• Sustain or increase support level through duration of CMI project.

may-oct 2003 review – optical properties of nanoscale arrays, cmi-001; fabricate voltage-tunable...

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