Vertical cavity surface emitting laser with undoped top mirror
First Claim
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1. A method of fabricating a VCSEL comprising:
- forming a bottom mirror on a substrate, wherein forming a bottom mirror comprises forming alternating layers of materials with different indices of refraction with ramps between the alternating layers of materials, each ramp having a step change in composition, wherein at least a portion of the materials are doped to a conductivity type of the substrate;
forming an active layer that contains quantum wells on the bottom mirror;
forming a periodically doped conduction layer region that has an opposite conductivity type from the bottom mirror on and in contact with the active layer, wherein forming the periodically doped conduction layer region comprises doping portions of the conduction layer region more heavily at a location where the optoelectronic energy is at about a minimum when the VCSEL is in use;
forming a thermally conductive top mirror on the conduction layer region such that the top mirror is essentially undoped and non-graded; and
forming a thermally conductive intracavity contact layer on the first conduction layer and that extends to and at least partially covers a top of the top mirror.
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Abstract
A VCSEL with undoped top mirror. The VCSEL is formed from an epitaxial structure deposited on a substrate. A doped bottom mirror is formed on the substrate. An active layer that includes quantum wells is formed on the bottom mirror. A periodically doped conduction layer is formed on the active layer. The periodically doped conduction layer is heavily doped at locations where the optical energy is at a minimum when the VCSEL is in operation. A current aperture is used between the conduction layer and the active region. An undoped top mirror is formed on the heavily doped conduction layer.
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Citations
20 Claims
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1. A method of fabricating a VCSEL comprising:
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forming a bottom mirror on a substrate, wherein forming a bottom mirror comprises forming alternating layers of materials with different indices of refraction with ramps between the alternating layers of materials, each ramp having a step change in composition, wherein at least a portion of the materials are doped to a conductivity type of the substrate; forming an active layer that contains quantum wells on the bottom mirror; forming a periodically doped conduction layer region that has an opposite conductivity type from the bottom mirror on and in contact with the active layer, wherein forming the periodically doped conduction layer region comprises doping portions of the conduction layer region more heavily at a location where the optoelectronic energy is at about a minimum when the VCSEL is in use; forming a thermally conductive top mirror on the conduction layer region such that the top mirror is essentially undoped and non-graded; and forming a thermally conductive intracavity contact layer on the first conduction layer and that extends to and at least partially covers a top of the top mirror. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of forming a VCSEL, the method comprising:
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providing a substrate of a first conductivity type; and forming an epitaxial structure on the substrate, wherein forming the epitaxial structure includes; forming a bottom DBR mirror on the substrate wherein the bottom mirror is doped to the first conductivity type and wherein the bottom DBR mirror comprises alternating layers of AlAs and GaAs with ramps between the AlAs and GaAs layers, the ramps including a step change to AlGaAs with at least 30% aluminum and an essentially continuous ramp of decreasing aluminum composition between the step change and the GaAs layer; forming an active layer on the bottom mirror, the active layer including quantum wells; forming a periodically doped first conduction layer of a second conductivity type, the first conduction layer at least partially contacting the active layer, the doped first conduction layer being heavily doped at a location where the optical electric field is at about a minimum; forming an aperture formed in the epitaxial structure above the quantum wells; forming a thermally conductive top mirror coupled to the periodically doped first conduction layer, the top mirror forming a mesa structure having a lateral wall, wherein the top mirror is essentially undoped, the top mirror having alternating layers that are substantially non-graded at an interface between the alternating layers so as to increase heat conduction through the top mirror; forming a thermally conductive intracavity contact layer having a first portion that is deposited on the first conduction layer and a second portion formed above the first portion wherein the second portion completely covers the lateral wall of the mesa structure and at least partially covers the top of the mesa structure so as to conduct heat from the mesa structure, wherein the second portion does not block the aperture; and configuring the VCSEL such that the active region, top mirror, and bottom mirror are capable of emitting a laser beam from the top mirror.
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Specification