QuNano AB Nanowhiskers Form Electronic, Photonic, MEMS Devices and Artificial Nerves That May Cure Some Blindness

QuNano AB (Lund, SE) inventors Lars Ivar Samuelson and Bjorn Jonas Ohlsson created a resonant tunneling diode, and other one dimensional electronic, photonic structures, and electromechanical MEMS devices that are formed as a heterostructure in a nanowhisker by forming length segments of the whisker with different materials having different band gaps.

In one aspect a substrate, for example of silicon, has a matrix of electrical contact areas formed on one surface. On each contact area, one, or a number, of nanowhiskers are formed from, for example, gold catalyst particles so as to be upstanding from the substrate's surface. Each nanowhisker, or group of nanowhiskers may therefore be individually addressable by electrical signals. Such a structure may make contact with the end of a nerve or perhaps the nerves in the retina of an eye, and the electrodes may be activated so as to provide a repairing or artificial function for enabling the nerve. Thus for example, when applied in the retina of an eye, the structure may overcome certain blindness problems

U.S. Patent 7,682,943 details QuNano’s method of forming nanowhiskers, one-dimensional semiconductor nanocrystals, in which segments of the whisker have different compositions, for example indium arsenide whiskers containing segments of indium phosphide.  The conditions for growth allow the formation of abrupt interfaces and heterostructure barriers of thickness from a few monolayers to hundreds of nanometers, thus creating a one-dimensional landscape along which electrons can move.  

In a preferred method of the chemical beam epitaxy method (CBE), rapid alteration of the composition is controlled by the supply of precursor atoms into a eutectic melt of seed particle and substrate, supplied as molecular beams into the ultra high vacuum chamber. The rapid switching between different compositions is obtained via a sequence where growth is interrupted or at least reduced to an insignificant amount, and supersaturation conditions for growth are reestablished; at least, change of composition and supersaturation is changed faster than any appreciable growth. With abrupt changes in material of the whisker, stresses and strains arising from lattice mismatch are accommodated by radial outward bulging of the whisker, or at least by lateral displacement of the atoms in the lattice planes near the junction. 

This Chemical Beam Epitaxy method permits formation of heterojunctions within a nanowhisker, which are abrupt, in the sense there is a rapid transition from one material to another over a few atomic layers

Further, the invention includes a technique for the synthesis of size-selected, epitaxial nano-whiskers, grown on a crystalline substrate. As catalysts, size-selected gold aerosol particles are used, which enables the surface coverage to be varied completely independently of the whisker diameter. The whiskers were rod shaped, with a uniform diameter between 10 and 50 nm, correlated to the size of the catalytic seed. By the use of nano-manipulation of the aerosol particles, individual nano-whiskers can be nucleated in a controlled manner at specific positions on a substrate with accuracy on the nm level.

The method enhances width control of the whisker by virtue of choice of nanoparticle. The nanoparticle may be an aerosol or a liquid alloy on the substrate may be made by starting from gold rectangles formed on the substrate which when melted form accurate diameter balls. Other materials may be used instead of gold as the seed particle such as gallium.

Founded in 2005, QuNano AB is a venture-backed, development-stage nanotechnology company focused on development and commercialization of next generation quantum nanoscale semiconductor materials and devices for the electronics, optoelectronics and sensor markets based on its proprietary heterostructured nanowire epitaxial growth and process technologies.

QuNano AB
Scheelevägen 17
Ideon Science Park
223 70 Lund Sweden

Tel. +46 46 286 4840

http://www.qunano.com/m.