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Optical device structure using GaN substrates and growth structures for laser applications

  • US 8,969,113 B2
  • Filed: 03/28/2014
  • Issued: 03/03/2015
  • Est. Priority Date: 04/13/2009
  • Status: Active Grant
First Claim
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1. A method for manufacturing an optical device, the method comprising:

  • providing a gallium and nitrogen containing substrate member having a semipolar crystalline surface region, the gallium and nitrogen containing substrate member having a thickness of less than 500 microns, the gallium and nitrogen containing substrate member characterized by a dislocation density of less than 107 cm

    2
    , the semipolar crystalline surface region having a root mean square surface roughness of 10 nm or less over a 5 micron by 5 micron analysis area, the semipolar crystalline surface region being characterized by a specified off-set from a (20-21) semipolar plane;

    forming a surface reconstruction region overlying the semipolar crystalline surface region, the surface reconstruction region having an oxygen bearing concentration of greater than 1E17 cm

    3
    ;

    forming an n-type cladding layer comprising a first quaternary alloy, the first quaternary alloy comprising an aluminum bearing species, an indium bearing species, a gallium bearing species, and a nitrogen bearing species overlying the semipolar crystalline surface region, the n-type cladding layer having a thickness from 100 nm to 4000 nm with an n-type doping level of 1E17 cm

    3
    to 6E18 cm

    3
    ;

    forming a first gallium and nitrogen containing epitaxial material comprising a first portion characterized by a first indium concentration, a second portion characterized by a second indium concentration, and a third portion characterized by a third indium concentration overlying the n-type cladding layer;

    forming an n-side separate confining heterostructure (SCH) waveguiding layer overlying the n-type cladding layer, the n-side SCH waveguiding layer comprising InGaN with a molar fraction of InN of between 1% and 8% and having a thickness from 30 nm to 150 nm;

    forming a multiple quantum well active region overlying the n-side SCH waveguiding layer, the multiple quantum well active region comprising two to five InGaN quantum wells having a thickness from 2.0 nm to 4.5 nm and being separated by gallium and nitrogen containing barrier layers having a thickness from 7.5 nm to 18 nm;

    forming a p-side guide layer overlying the multiple quantum well active region, the p-side guide layer comprised of GaN or InGaN and having a thickness from 20 nm to 100 nm, the InGaN having a molar fraction of InN of between 1% and 5%;

    forming a second gallium and nitrogen containing material overlying the p-side guide layer;

    forming a p-type cladding layer comprising a second quaternary alloy overlying the second gallium and nitrogen containing material, the p-type cladding layer having a thickness from 300 nm to 1000 nm with a magnesium doping level of 1E17 cm

    3
    to 3E19 cm

    3
    ;

    causing formation of a plurality of hydrogen species, the plurality of hydrogen species spatially disposed within the p-type cladding layer; and

    forming a p++ gallium and nitrogen containing contact layer overlying the p-type cladding layer, the p++ gallium and nitrogen containing contact layer having a thickness from 10 nm to 100 nm and a magnesium doping level of 2E19 cm

    3
    to 1E22 cm

    3
    ;

    forming a waveguide member using an etching process, the waveguide member being aligned substantially in a projection of the c-direction, the waveguide member comprising a first end and a second end, the waveguide member having a first edge region formed on a first side of the waveguide member, the waveguide member having a second edge region formed on a second side of the waveguide member;

    maintaining the etching process from causing any damage to the multiple quantum well active region;

    forming a first facet on the first end, the first facet being characterized by a first semipolar characteristic; and

    forming a second facet on the second end, the second facet being characterized by a second semipolar characteristic;

    whereupon the waveguide member is provided between the first facet and the second facet, the waveguide member having a length of greater than 300 microns and configured to emit substantially polarized electromagnetic radiation such that a polarization is substantially orthogonal to the waveguide member direction and the polarized electromagnetic radiation having a wavelength of 500 nm and greater and a spontaneous emission spectral full width at half maximum of less than 50 nm in a light emitting diode mode of operation.

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