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Monolayered opalline super lattice: application to nanotechnology of 2D ordered array of epitaxial nanodots and metalattice conductors

Project information

Grant agreement ID: INTAS-2001-00796

  • Start date

    1 July 2002

  • End date

    31 October 2004

Funded under:

IC-INTAS

Coordinated by:

CSIC

Spain

Objective

Materials with spatially ordered particles on nanometer scale manifest new properties promising in many potential applications. Within the project three of them with regards to fabrication of high quality periodic epitaxial nanostructures are considered with motivation of the research as following as
- Mainly driven by the needs of the information technology, semiconductors light-emitting materials have reached a level of sophistication that surpassed that of any other light-emitting material known to man, with internal quantum efficiencies above 90% being routinely obtained. Laser diodes are a new type of semiconductor light-emitting device. They rely on stimulated emission and are therefore more efficient that LED, but are not applicable to every problem. Photonic crystals represent this concept;
- High-density magnetic memory is another challenge for nanotechnology.

It is well known problem how to fabricate small magnets while controlling their size, shape and crystalline quality, and how to assemble them into well-ordered array. Spin-polarised electron transport is a new field of application of magnetic materials, as well. Electron itself as a particle carries both charge and spin. When latter controls electron transport, it becomes to depend on magnetic confinement. New term "spintronics" becomes apparent. Giant magnetoresistance is new example that belongs to the effect of spin-polarised electron transport.
- Recently, new class of metal-based materials (conductors) that combines quantum confinement with three (it is supposed 2D, as well) dimensional delocalised, dispersive electron states has been proposed theoretically. These materials consisted of underlying atomic structure resides within the larger periodic colloids, where their size of 1-10 nm is desirable. This material structure is referred as a metalattice.
Consortium of the teams from Russia (two), Moldova, UK and Spain considers the development of "sphere lithography" as a prospective way for fabrication of 2D well-ordered array of epitaxial nanodots and metalattices, pointed potential applications of the interest. It is suggested that this improvement should go through by application of monolayered opalline superlattice (with the period of 10-300 nm) as an inorganic nanomask to nanotechnology of epitaxial materials with spatially 2D-ordered particles. Opalline nanomask is compatible the high temperature and atomically clean substrate, needed for the high quality epitaxial growth of solid films. Within the project this approach is applied to fabrication of 2D periodic array of epitaxial well-shaped ZnO quantum dots, magnetic dots and metalattice conductors of (100) Ni (Fe, Co) and normal metal (100) W (Mo) with 2D-period of 10-300 nm. Their electron structure, optical, magnetic and electron transport properties will be investigated with regards to potential applications: 2D photonic band gap crystals, high density magnetic memory, giant magnetoresistance and new type metallic metalattice conductors, respectively.
The experience of the teams that involved into the consortium, equipment and techniques together with preliminary experimental results that they possess are complementary each other. It covers whole scope of the project making its fulfilment to be visible.
Within the project the scientific activities concern: growth of opal spheres and fabrication of 2D opal matrixes (T1.1); characterization and thermal or plasma treatment of 2D opal matrix to prepare the nanomask for clean conditions, followed by epitaxial growth of the materials (T1.2); fabrication of epitaxial 2D ordered structures, that includes as (A) - direct epitaxial deposition under UHV conditions of ZnO (Ni, W) on c- (r-) plane sapphire through opalline nanomask, followed by "lift-off" of opalline spheres, and as (B) - etching high quality epitaxial thin films, preliminary grown, that beneath the nanomask (T2). Within these approaches it is looking for successful fabrication of 2D-ordered array of epitaxial nanodots (A) (it possess inversed structure of opalline nanomask), which properties are investigated in T3 - optical properties of ZnO nanodots array, that include luminescence, stimulated emission and luminescence, SNOM experiments, and also in T4.2 - magnetization of Ni nanodots array, that include MOKE and MFM experiments. Type B structures that are also referred as metalattice films (conductors) are investigated in T4.2, where electron transport experiments for four terminal bridge type nanostructures, composed from metalattice films, are carried out with regards to giant magnetoresistance effect (for Ni-conductors) and quantum confinement effect for W-conductors.
Task 5 is devoted to electron structure investigation of 2D-ordered array of epitaxial nanodots and metalattices in UHV conditions by electron spectroscopy: valence band structure (DOS) and electron excitations. The spectroscopic data for both fabricated array and bulk materials will be compared. The other subtasks (T1.2, T3.1, T4.1, T5.1) serve for geometrical, crystalline and compositional characterization of both opalline nanomask and 2D-ordered arrays of particles.
Scientific activities, described above, directed to nanotechnology development of 2D-ordered array of epitaxial nanodots and metalattices with the help of inorganic nanomask - monolayered opalline superstructure, that is also the aim of the project. It is supposed that the results of the project would be fruitful for nanotechnology and basic research.

Coordinator

CSIC

Address

Isaac Newton, 8
28760 Tres Cantos, Madrid

Spain

Participants (4)

Institute of Microelectronics Technology and High Purity Materials

Russia

Queen's University of Belfast

United Kingdom

Russian Academy of Sciences

Russia

Technical University of Moldova

Moldova

Project information

Grant agreement ID: INTAS-2001-00796

  • Start date

    1 July 2002

  • End date

    31 October 2004

Funded under:

IC-INTAS

Coordinated by:

CSIC

Spain