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.
Claims20
A semiconductor laser comprising:
- an active region for generating light output within a defined area of the active region in response to an electrical current passing therethrough;
- a semiconductor substrate;
- a lower cladding layer of a first conductivity type disposed between the semiconductor substrate and the active region;
- an upper cladding layer of a second, opposite conductivity type disposed over an exposed upper surface of the active region;
- 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 current blocking layer disposed between the lower cladding layer and the active region, the current blocking layer comprising a high resistivity material and formed to include a low resistivity central area substantially coinciding in location and topology with the light-generating defined area of the active region, guiding upward current flow from the second ohmic contact away from the high resistivity regions of the current blocking layer and toward the low resistivity central area.
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) forming a current blocking layer over the semiconductor substrate, the current blocking layer comprising a layer of highly resistive material, with central area of lower resistivity;
- and
- c) fabricating a semiconductor laser device over the highly resistive layer, the laser device comprising an active region formed between opposite conductivity cladding layers, the active region defined to support an optical mode having a width aligned with, and substantially the same size as, the central area of the current blocking layer.
Dependencies are inferred from the claim text.