Available Technology

Atomically Flat Crystal Surfaces IB-2549

Devices once fabricated at micron-level precision are now fabricated at nano-level precision. With the trend continuing towards miniaturization, material imperfections, even at the atomic scale, will affect performance of semiconductors and electronic devices such as hard drive readers. Farid El Gabaly and Andreas K. Schmid of Berkeley Lab have invented a simple, self-assembling method to prepare ultraflat crystal surfaces on very large regions of a material substrate. Currently, a surface must either be lithographically pre-patterned to achieve extended atomically flat surface regions, or a crystal surface must be searched until an isolated, naturally formed flat region is found. The former process is expensive; the latter is inefficient since even the most highly polished crystals can be populated with a high density of steps when viewed at the nano-scale. In the Berkeley Lab method, atomic layers of a different material are applied to the substrate. Either by the Stransky-Krastanov or the Vollmer-Weber growth mode, self-assembled, micron size, 3D islands with atomically flat top facets grow over the entire surface. These islands have a stepped interface with the substrate crystal underneath. The surface morphology is then transferred to the substrate crystal using sputter etching until the overlay material is completely removed and all that is left is the imprinting of the islands on the substrate surface. After an additional annealing process, the surface preparation is complete. This technology creates arrays of ultraflat, defect free areas alternating with stepped areas.Selection of the overlayer material as well as deposition rate and temperature can be adjusted to fine tune the outcome for different industrial needs.
Benefits: 
Simple, self-assembling - Doesn’t require lithographic pre-patterning of the surface - Low cost - Can be used for wide range of materials
applications: 
Internal Laboratory Ref #: 
IB-2549
Patent Status: 
Published Patent Application PCT/US2009/036619 available at www.wipo.int. Available for licensing or collaborative research.
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