University of Houston System

USA As Represented by Secretary of the Navy

Terry D Golding

John H Miller, Jr

Jerry R Meyer

Filbert J Bartoli

Craig A Hoffman

Eric R Youngdale

Jaiming Huang

The present invention provides for the fabrication of single layer semimetal/semiconductor heterostructures and multilayer semimetal/semiconductor structures. Each semimetal/semiconductor layer fabricated in accordance with the present invention has compatible crystal symmetry across the heterojunction between a semimetal and a semiconductor. A single layer semimetal/semiconductor structure is fabricated by growing a rhombohedral semimetal in a �111! direction on a substrate material having a (111) orientation, and then growing a zincblende semiconductor in a �111! direction on the semimetal. A multilayer semimetal/semiconductor structure may be grown from the single layer semimetal/semiconductor structure by growing an additional rhombohedral semimetal layer in a �111! direction on the preceding semiconductor grown, then growing an additional zincblende semiconductor layer in a �111!direction on the additional semimetal layer, and then repeating this process as many times as desired. Each semimetal to be sandwiched between semiconductors in the multilayer semimetal/semiconductor structure may be grown thin enough that the semimetal is converted into a semiconductor.

Semimetal-semiconductor heterostructures and multilayers

The present invention relates to novel optical devices operating in the infrared, based on indirect narrow-gap superlattices (INGS) as the active optical materials. The novel optical devices include (1) wideband all-optical switches, which combine small insertion loss at low light intensities with efficient optical switching and optical limiting at high intensities, and (2) wideband infrared detectors with high collection efficiency and low tunneling noise currents, suitable for use in longwave infrared focal plane arrays. INGS comprise multiple semimetal/semiconductor layers having compatible crystal symmetry across each heterojunction between a given semimetal and the adjoining semiconductor, wherein each semimetal layer sandwiched between semiconductor layers is grown thin enough that each semimetal layer becomes a semiconductor, and wherein each semiconductor layer is thin enough that there is coupling between adjacent semiconductor layers. The present invention utilizes INGS, which are fabricated to meet the criteria E.sub.g.sup.ind &lt;h.omega.&lt;E.sub.g.sup.dir, especially where h.omega.&lt;100 meV, as the optical material for optical switches. The present invention also utilizes INGS as optical detectors if they are fabricated such that E.sub.g.sup.ind &lt;E.sub.g.sup.dir &lt;h.omega., especially where h.omega. is less than 155 meV.

Optical switches and detectors utilizing indirect narrow-gap

The present invention provides for the fabrication of single layer semimetal/semiconductor heterostructures and multilayer semimetal/semiconductor structures. Each semimetal/semiconductor layer fabricated in accordance with the present invention has compatible crystal symmetry across the heterojunction between a semimetal and a semiconductor. A single layer semimetal/semiconductor structure is fabricated by growing a rhombohedral semimetal in a [111] direction on a substrate material having a (111) orientation, and then growing a zincblende semiconductor in a [111] direction on the semimetal. A multilayer semimetal/semiconductor structure may be grown from the single layer semimetal/semiconductor structure by growing an additional rhombohedral semimetal layer in a [111] direction on the preceding semiconductor grown, then growing an additional zincblende semiconductor layer in a [111] direction on the additional semimetal layer, and then repeating this process as many times as desired. Each semimetal to be sandwiched between semiconductors in the multilayer semimetal/semiconductor structure may be grown thin enough that the semimetal is converted into a semiconductor.

A physical configuration for a parallel multi-junction superconducting quantum interference device that can be used for a variety of applications involving the detection of magnetic flux, including applications where it is desired to measure the absolute magnitude of the flux. The device of this invention features a novel geometry for a multi-junction interference device which significantly enhances the flux-to-voltage transfer function, thereby yielding a significant improvement in the device sensitivity in its use in a magnetometer, gradiometer, or other applications.

Growing community of inventors

Missouri City, TX, United States of America

Terry D Golding