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Methods for controllable doping of aluminum nitride bulk crystals

  • US 8,012,257 B2
  • Filed: 03/30/2007
  • Issued: 09/06/2011
  • Est. Priority Date: 03/30/2006
  • Status: Active Grant
First Claim
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1. A method of forming polycrystalline AlN, the method comprising the steps of:

  • providing within a crucible a pellet comprising Al, the crucible comprising a foil wrap;

    reacting the pellet at a reaction temperature and a reaction pressure with nitrogen gas to form a bulk polycrystalline AlN ceramic, wherein, when the polycrystalline AlN ceramic reaches approximately room temperature after the reaction, the polycrystalline AlN ceramic having properties including (i) less than approximately 1% excess Al and (ii) an oxygen concentration of less than approximately 100 ppm;

    after forming the polycrystalline AlN ceramic, and with no sublimation-recondensation treatment of the polycrystalline AlN ceramic therebetween, providing the polycrystalline AlN ceramic and at least a portion of the foil wrap at a first end of and within a crystal growth enclosure;

    subliming the polycrystalline AlN ceramic at a formation temperature, the at least a portion of the foil wrap remaining in contact with the polycrystalline AlN ceramic thereduring; and

    forming an AlN single crystal at a second end of the crystal growth enclosure.

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