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Vertical cavity surface emitting laser with low band gap highly doped contact layer

  • US 5,818,861 A
  • Filed: 07/19/1996
  • Issued: 10/06/1998
  • Est. Priority Date: 07/19/1996
  • Status: Expired due to Term
First Claim
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1. In a vertical cavity surface emitting laser having at least a substrate, a lower distributed Bragg reflector, an active region generating light, and an upper distributed Bragg reflector, a contact structure comprising:

  • a plurality of current spreading layers overlying the upper distributed Bragg reflector, the current spreading layer closest to the upper distributed Bragg reflector having a dopant concentration approximately equal to that of the upper distributed Bragg reflector and successive current spreading layers having increasing dopant concentrations;

    a degeneratively doped layer comprising a low bandgap material overlying the current spreading layers, the doping concentration of the current spreading layer underlying the degeneratively doped layer having a doping concentration approximately the same as the degeneratively doped layer; and

    a surface metal contact overlying portions of the degeneratively doped layer, the combination of the current spreading layers, the degeneratively doped layer, and the surface metal contact providing a low resistance current path from the surface contact to the active region.

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