Vertical cavity surface emitting laser with low band gap highly doped contact layer
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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Abstract
A contact structure for a vertical cavity surface emitting laser is described. The contact structure comprises a surface metal contact, a degeneratively doped layer of low bandgap material less than 200 Å thick, and a plurality of current spreading layers. The contact structure provides a low ohmic path between the metal contact and the active region of the vertical cavity surface emitting laser.
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Citations
5 Claims
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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:
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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. - View Dependent Claims (2, 3, 4, 5)
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Specification