Patents by Inventor Stephen R. Lee

Stephen R. Lee has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Strain-relaxed InGaN-alloy template
    Publication number: 20210013373
    Abstract: The invention is directed to a method for fabricating strain-relaxed InGaN-alloy templates with higher indium compositions, reduced threading-dislocation densities, improved surface morphologies, and lowered point-defect densities. The method employs nanopatterns fabricated onto the surface of GaN-based templates or bulk-GaN substrates using conventional semiconductor processing. The nanopatterns are specifically designed to enable maskless nanoepitaxial growth of InGaN alloys while simultaneously promoting combined elastic and plastic strain relaxation during nanoepitaxy of InGaN alloys in a manner that raises alloy compositions and reduces defect formation. These templates enable subsequent growth of III-Nitride optoelectronics operating at wavelengths spanning most of the visible-light spectrum while simultaneously enabling higher efficiencies than attained using strain-relaxed InGaN alloys grown by conventional planar heteroepitaxy.
    Type: Application
    Filed: July 9, 2019
    Publication date: January 14, 2021
    Inventor: Stephen R. Lee
  • Aluminum nitride transitional layer for reducing dislocation density and cracking of AlGaN epitaxial films
    Patent number: 8349633
    Abstract: A denticulated Group III nitride structure that is useful for growing AlxGa1-xN to greater thicknesses without cracking and with a greatly reduced threading dislocation (TD) density.
    Type: Grant
    Filed: May 26, 2009
    Date of Patent: January 8, 2013
    Assignee: Sandia Corporation
    Inventors: Andrew A. Allerman, Mary H. Crawford, Stephen R. Lee
  • Aluminum nitride transitional layer for reducing dislocation density and cracking of AIGan epitaxial films
    Patent number: 7915626
    Abstract: A denticulated Group III nitride structure that is useful for growing AlxGa1-xN to greater thicknesses without cracking and with a greatly reduced threading dislocation (TD) density.
    Type: Grant
    Filed: August 15, 2006
    Date of Patent: March 29, 2011
    Assignee: Sandia Corporation
    Inventors: Andrew A. Allerman, Mary H. Crawford, Daniel D. Koleske, Stephen R. Lee
  • Distributed bragg reflector using AIGaN/GaN
    Patent number: 6775314
    Abstract: A supported distributed Bragg reflector or superlattice structure formed from a substrate, a nucleation layer deposited on the substrate, and an interlayer deposited on the nucleation layer, followed by deposition of (Al,Ga,B)N layers or multiple pairs of (Al,Ga,B)N/(Al,Ga,B)N layers, where the interlayer is a material selected from AlN, AlxGa1-xN, and AlBN with a thickness of approximately 20 to 1000 angstroms. The interlayer functions to reduce or eliminate the initial tensile growth stress, thereby reducing cracking in the structure. Multiple interlayers utilized in an AlGaN/GaN DBR structure can eliminate cracking and produce a structure with a reflectivity value greater than 0.99.
    Type: Grant
    Filed: November 29, 2001
    Date of Patent: August 10, 2004
    Assignee: Sandia Corporation
    Inventors: Karen E. Waldrip, Stephen R. Lee, Jung Han