Control Of Current Spread In Semiconductor Laser Devices
AssigneeII-Vi Delaware, Inc.
InventorsEvgeny Zibik, Wilfried Maineult
Life of this patent
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Abstract
A semiconductor laser is formed to include a current blocking layer that is positioned below the active region of the device and used to minimize current spreading beyond the defined dimensions of an output beam's optical mode. When used in conjunction with other current-confining structures typically disposed above the active region (e.g., ridge waveguide, electrical isolation, oxide aperture), the inclusion of the lower current blocking layer improves the efficiency of the device. The current blocking layer may be used in edge-emitting devices or vertical cavity surface-emitting devices, and also functions to improve mode shaping and reduction of facet deterioration by directing current flow away from the facets.
Claims16
A semiconductor laser, comprising
- a lower cladding layer of a first conductivity type;
- an upper cladding layer of a second, opposite conductivity type;
- an active region disposed as a layer between the lower cladding layer and the upper cladding layer, the active region including a light-generating central area configured to produce a laser output in response to an electrical current passing therethrough;
- a semiconductor substrate disposed below the lower cladding layer;
- a first ohmic contact disposed on the upper cladding layer;
- a second ohmic contact disposed on a exposed bottom surface of the semiconductor substrate;
- and
- a high resistivity current blocking layer formed within the lower cladding layer and including a low resistivity central region substantially coinciding in location and topology with the defined central area of the active region, the high resistivity current blocking layer directing conductor flow from the second ohmic contact through the low resistivity central region and into the light-generated central area of the active region.
A method of fabricating a current-confined semiconductor laser structure, including the steps of:
- a) providing a semiconductor substrate upon which a laser diode structure is to be formed;
- b) depositing a layer of current blocking material across an exposed upper surface of the semiconductor substrate, the layer of current blocking material including a central area exhibiting a lower resistivity than the remainder of the layer of current blocking material;
- and
- c) fabricating a semiconductor laser device on the layer of current blocking material, the semiconductor laser device including an active region defined to support an optical mode in a central portion thereof, wherein the central portion of the active region is disposed substantially in alignment with lower resistivity central area of the layer of current blocking material.
Dependencies are inferred from the claim text.