University of California

USA As Represented by Secretary of the Navy

Eicke R Weber

Peidong Yang

Timothy David Sands

Rong Fan

Richard E Russo

Ali Shakouri

Samuel S Mao

Arun Majumdar

Hannes Kind

Haoquan Yan

Yiying Wu

Henning Feick

Michael Huang

Todd Russell Weatherford

Sudhir G Subramanya

Mathew A Marcus

Petra Specht

Robert D Armitage

Yihwan Kim

Joachim Kruger

Anthony Buonassisi

Matthias Heuer

Andrei A Istratov

Matthew D Pickett

One-dimensional nanostructures having uniform diameters of less than approximately 200 nm. These inventive nanostructures, which we refer to as 'nanowires', include single-crystalline homostructures as well as heterostructures of at least two single-crystalline materials having different chemical compositions. Because single-crystalline materials are used to form the heterostructure, the resultant heterostructure will be single-crystalline as well. The nanowire heterostructures are generally based on a semiconducting wire wherein the doping and composition are controlled in either the longitudinal or radial directions, or in both directions, to yield a wire that comprises different materials. Examples of resulting nanowire heterostructures include a longitudinal heterostructure nanowire (LOHN) and a coaxial heterostructure nanowire (COHN).

Methods of fabricating nanostructures and nanowires and devices fabricated therefrom

The present invention relates to the internal gettering of impurities in semiconductors by metal alloy clusters. In particular, intermetallic clusters are formed within silicon, such clusters containing two or more transition metal species. Such clusters have melting temperatures below that of the host material and are shown to be particularly effective in gettering impurities within the silicon and collecting them into isolated, less harmful locations. Novel compositions for some of the metal alloy clusters are also described.

Internal gettering by metal alloy clusters

The present invention relates to the production of thin film epilayers of III&#x2013;V and other compounds with acceptor doping wherein the acceptor thermally stabilizes the epilayer, stabilize the naturally incorporated native defect population and therewith maintain the epilayer's beneficial properties upon annealing among other advantageous effects. In particular, balanced doping in which the acceptor concentration is similar to (but does not exceed) the antisite defects in the as-grown material is shown to be particularly advantageous in providing thermal stability, high resistivity and ultrashort trapping times. In particular, MBE growth of LT-GaAs epilayers with balanced Be doping is described in detail. The growth conditions greatly enhance the materials reproducibility (that is, the yield in processed devices). Such growth techniques can be transferred to other III&#x2013;V materials if the growth conditions are accurately reproduced. Materials produced herein also demonstrate advantages in reproducibility, reliability and radiation hardening.

Doping-assisted defect control in compound semiconductors

Gallium nitride is grown by plasma-assisted molecular-beam epitaxy on (111) and (001) silicon substrates using hafnium nitride buffer layers. Wurtzite GaN epitaxial layers are obtained on both the (111) and (001) HfN/Si surfaces, with crack-free thickness up to 1.2m. However, growth on the (001) surface results in nearly stress-free films, suggesting that much thicker crack-free layers could be obtained.

Hafnium nitride buffer layers for growth of GaN on silicon

Nanowires, nanostructures and devices fabricated therefrom

A novel growth procedure to grow epitaxial Group III metal nitride thin films on lattice-mismatched substrates is proposed. Demonstrated are the quality improvement of epitaxial GaN layers using a pure metallic Ga buffer layer on c-plane sapphire substrate. X-ray rocking curve results indicate that the layers had excellent structural properties. The electron Hall mobility increases to an outstandingly high value of &mgr;>400 cm /Vs for an electron background concentration of 4&times;10 cm .

Process for growing epitaxial gallium nitride and composite wafers

Growing community of inventors

Oakland, CA, United States of America

Eicke R Weber