Other

Martin Moskovits

Thomas L Haslett

Kejian Fu

Jing M Xu

Xijia Gu

Dmitri N Davydov

Jing Li

Konstantin B Shelimov

A perpendicular-mode near-field scanning optical microscope (NSOM) utilizing a piezoelectric micro tuning fork as its height-sensing element is described. The present invention provides a method and apparatus for modifying and attaching an optical fiber to the tuning fork that allows the assembly to retain Q-factors up to 9000, substantially higher than those described so far in the literature for tuning-fork-based instruments. The method involves reducing the diameter of the cladding of the optical fiber down to the 17-25 &mgr;m using several chemical etching steps, before the fiber is attached to the tuning fork. A sharp upturn in the Q-factor is observed when the fiber diameter d drops below &tilde;25 &mgr;m. An analysis, which shows that the stretching force constant of a bent fiber is proportional to d , is used to account for the great sensitivity of the Q-factor to the fiber diameter. The high Q-factors resulted in improved force sensitivity and allowed us to construct a perpendicular mode instrument without the use of additional dithering piezoelements. An improved NSOM operating in the sear force mode is also provided by thinning the optical fiber length running down the length of one of the tines to a thickness in the range from about 50 to 60 &mgr;m.

Near-field scanning optical microscope with a high Q-factor piezoelectric sensing element

The present invention provides a powerful new method for producing, uniform sized and uniformly aligned nanotubes through catalytic pyrolysis of a hydrocarbon within the dense, uniform and parallel pores of alumina nano-templates. The catalyst, Co, Fe, Ni or another suitable substance is deposited electrochemically into the bottom of the channel of the alumina template. The nanotubes with any desired diameter in the range 5-500 nm and lengths up to .about.100 .mu.m, are generated by the pyrolysis of a suitable hydrocarbon inside the pores of the alumina template with at least one end open at the alumina/air interface. The nanotubes may be filled by metals using for example electroless deposition.

Controlled synthesis and metal-filling of aligned carbon nanotubes

A method of growing single crystal diamonds in excess of 10 .mu.m in diameter from industrial diamond 'seeds' having mean diameters of approximately 1.5 .mu.m is disclosed. The diamonds are grown by exposing the seed diamonds to C.sub.70 in the presence of elemental reducing agents such as phosphorus or selenium in evacuated cells at moderate temperatures and pressures. In another aspect the invention diamonds are grown by exposing diamond seed particles to vapour phase C.sub.70 in the presence of a gas phase metal carbonyl, such as F.sub.5 e(CO) in a temperature range of 400.degree. C. to 700.degree. C. to cause at least some of the diamond seed particles to grow.

Process of diamond growth from C.sub.70

A method of growing diamond crystals in excess of 10 .mu.m in diameter from industrial diamond 'seeds' having mean diameters of approximately 1.5 .mu.m is disclosed. The diamonds are grown by exposing the seed diamonds to C.sub.70 in the presence of reducing agents such as phosphorus or selenium in evacuated cells at moderate temperatures and pressures.

Single-electron devices useful as diodes, transistors or other electronic components are prepared by anodizing a metal substrate in sheet or foil form electrolytically in an acid bath, to deposit thereon an oxide film having axially disposed micropores of substantially uniform diameter in the range of from about 1 to about 500 nanometers and substantially uniform depth less than the thickness of the oxide film, leaving an ultra thin oxide layer between the bottom of each pore in the metal substrate. The conductive material is deposited in the pores to form nanowires contacting the oxide layer at the bottom of the pores. Macro metal is deposited over the ends of the nanowires for external electrical contact purposes. Devices can be made according to the present invention which are suitable to exhibit single-electron tunnelling effects and arrays of tunnel junction devices can be prepared having a density up to the order of 10.sup.10 per square cm.

Nanoelectric devices

Quantum dot and quantum wire semiconductors in the nanosize range are produced by a process which utilizes a microporous aluminum oxide surface layer on an aluminum metal substrate as a template for the semiconducting material. The microporous surface layer is prepared by anodizing an aluminum substrate in an acid bath. Then a metal capable of forming a semiconductor compound is electrodeposited into the surface micropores, the oxide is partially or wholly etched away, and the deposited metal is reacted with a liquid or gaseous reagent to convert it chemically to a semiconducting compound. By the process of the invention, there are produced quantum dot or quantum wire semiconductors in the form of an array of substantially mutually parallel, substantially uniform-sized rods of semiconductor material protruding from an electrically conductive substrate, each rod having a diameter less than 100 nanometers.

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Toronto, Canada

Martin Moskovits