# US 8,569,088 B2 · Semiconductor light-emitting element and manufacturing method thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,569,088 B2 - Document ID: US8569088B2 - Status: Granted - Kind: B2 - Application number: 13/621,065 - Filed: 2012-09-15 - Published: 2013-01-10 - Granted: 2013-10-29 - Earliest claimed: 2010-03-23 - Assignees: Panasonic Corporation - Applicants: Kenji Orita - Inventors: Kenji Orita - Web page: https://patentgrep.com/patent/US8569088B2 ## CPC - H10H 20/042: {Superluminescent diodes} - B82Y 20/00: Nanooptics, e.g. quantum optics or photonic crystals - H01S 5/0207: {Substrates having a special shape} - H01S 5/1085: {Oblique facets} - H01S 5/125: Distributed Bragg reflector [DBR] lasers - H01S 5/164: {with window regions comprising semiconductor material with a wider bandgap than the active layer} - H01S 5/2201: {in a specific crystallographic orientation} - H01S 5/3201: {incorporating bulkstrain effects, e.g. strain compensation, strain related to polarisation} - H01S 5/34333: {with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser} - H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES - H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL ## Abstract A semiconductor light-emitting element includes: a substrate; and a nitride semiconductor multilayer film provided on an upper surface of the substrate and including an active layer. A recess, a stepped portion, or a protruding portion is formed in an active layer or a layer that contacts a lower surface of the active layer. A ridge stripe, which has a front end facet and a rear end facet and serves as an optical waveguide, is formed in an upper part of the nitride semiconductor multilayer film. The distance from a lateral center of the ridge stripe to a lateral center of the recess, the stepped portion, or the protruding portion changes continuously or in stages from the front end facet toward the rear end facet. Bandgap energy of the active layer changes continuously or in stages from the front end facet toward the rear end facet. ## Claims ### Claim 1 A semiconductor light-emitting element, comprising: a substrate; and a nitride semiconductor multilayer film provided on an upper surface of the substrate and including an active layer that produces light during operation, wherein a recess, a stepped portion, or a protruding portion is formed in an active layer or a layer of the nitride semiconductor multilayer film which contacts a lower surface of the active layer, a ridge stripe, which has a front end facet and a rear end facet facing the front end facet and serves as an optical waveguide, is formed in an upper part of the nitride semiconductor multilayer film, a distance from a lateral center of the ridge stripe to a lateral center of the recess, the stepped portion, or the protruding portion changes continuously or in stages from the front end facet toward the rear end facet, and bandgap energy of the active layer changes continuously or in stages from the front end facet toward the rear end facet, wherein a depth of the recess, a depth of the stepped portion, or a height of the protruding portion changes continuously or in stages from the front end facet toward the rear end facet. ### Claim 2 (depends on 1) The semiconductor light-emitting element of claim 1, wherein the recess, the stepped portion, or the protruding portion extends along the ridge stripe, a distance from the lateral center of the ridge stripe to an end of the recess, the stepped portion, or the protruding portion decreases continuously from the front end facet toward the rear end facet, and the bandgap energy of the active layer decreases continuously from the front end facet toward the rear end facet. ### Claim 3 (depends on 1) The semiconductor light-emitting element of claim 1, wherein the recess, the stepped portion, or the protruding portion extends along the ridge stripe, a width of the recess, the stepped portion, or the protruding portion in a direction substantially perpendicular to a direction in which the ridge stripe extends decreases continuously from the front end facet toward the rear end facet, and the bandgap energy of the active layer decreases continuously from the front end facet toward the rear end facet. ### Claim 4 (depends on 1) The semiconductor light-emitting element of claim 1, wherein the front end facet is a light-emitting end facet, and an optical axis of the optical waveguide is tilted with respect to a normal to the light-emitting end facet. ### Claim 5 (depends on 1) The semiconductor light-emitting element of claim 1, wherein the recess, the stepped portion, or the protruding portion is formed in the substrate. ### Claim 6 A semiconductor light-emitting element, comprising: a substrate; and a nitride semiconductor multilayer film provided on an upper surface of the substrate and including an active layer that produces light during operation, wherein a recess a stepped portion, or a protruding portion is formed in an active layer or a layer of the nitride semiconductor multilayer film which contacts a lower surface of the active layer, a ridge stripe, which has a front end facet and a rear end facet facing the front end facet and serves as an optical waveguide, is formed in an upper part of the nitride semiconductor multilayer film, a distance from a lateral center of the ridge stripe to a lateral center of the recess, the stepped portion, or the protruding portion changes continuously or in stages from the front end facet toward the rear end facet, bandgap energy of the active layer changes continuously or in stages from the front end facet toward the rear end facet, and multiple ones of the recess, the stepped portion, or the protruding portion are provided discontinuously along the ridge stripe. ### Claim 7 (depends on 6) The semiconductor light-emitting element of claim 6, wherein a distance from the lateral center of the ridge stripe to an end of the recess, the stepped portion, or the protruding portion decreases from the front end facet toward the rear end facet. ### Claim 8 A semiconductor light-emitting element, comprising: a substrate; and a nitride semiconductor multilayer film provided on an upper surface of the substrate and including an active layer, wherein a recess, a stepped portion, or a protruding portion is formed in the active layer or a layer of the nitride semiconductor multilayer film which contacts a lower surface of the active layer, a ridge stripe, which has a front end facet and a rear end facet facing the front end facet and serves as an optical waveguide, is formed in an upper part of the nitride semiconductor multilayer film, and a depth of the recess, a depth of the stepped portion, or a height of the protruding portion changes continuously or in stages from the front end facet toward the rear end facet. ### Claim 9 (depends on 8) The semiconductor light-emitting element of claim 8, wherein a depth of the recess, a depth of the stepped portion, or a height of the protruding portion changes continuously or in stages from the front end facet toward the rear end facet. ### Claim 10 (depends on 8) The semiconductor light-emitting element of claim 8, wherein multiple ones of the recess, the stepped portion, or the protruding portion are provided discontinuously along the ridge stripe. ### Claim 11 (depends on 10) The semiconductor light-emitting element of claim 10, wherein a distance from the lateral center of the ridge stripe to an end of the recess, the stepped portion, or the protruding portion decreases from the front end facet toward the rear end facet. ### Claim 12 A method for manufacturing a semiconductor light-emitting element, comprising the steps of: (a) providing a recess, a stepped portion, or a protruding portion in a substrate or a semiconductor layer on the substrate, and then forming on an upper surface of the substrate or an upper surface of the semiconductor layer a nitride semiconductor multilayer film including an active layer that produces light during operation; and (b) forming in an upper part of the nitride semiconductor multilayer film a ridge stripe that has a front end facet and a rear end facet facing the front end facet and serves as an optical waveguide, wherein in the step (b), a depth of the recess, a depth of the stepped portion, or a height of the protruding portion changes continuously or in stages from the front end facet toward the rear end facet. ### Claim 13 (depends on 12) The method of claim 12, wherein the recess, the stepped portion, or the protruding portion extends along the ridge stripe, and in the step (b), the ridge stripe is formed so that a distance from a lateral center of the ridge stripe to an end of the recess, the stepped portion, or the protruding portion decreases continuously from the front end facet toward the rear end facet. ### Claim 14 (depends on 12) The method of claim 12, wherein the recess, the stepped portion, or the protruding portion extends along the ridge stripe, and in the step (b), the ridge stripe is formed so that a width of the recess, the stepped portion, or the protruding portion in a direction substantially perpendicular to a direction in which the ridge stripe extends decreases continuously from the front end facet toward the rear end facet. ### Claim 15 (depends on 12) The method of claim 12, wherein in the step (b), the ridge stripe is formed so that a distance from a lateral center of the ridge stripe to a lateral center of the recess, the stepped portion, or the protruding portion changes continuously or in stages from the front end facet toward the rear end facet, whereby bandgap energy of the active layer is changed continuously or in stages from the front end facet toward the rear end facet. ### Claim 16 A method for manufacturing a semiconductor light-emitting element, comprising the steps of: (a) providing a recess, a stepped portion, or a protruding portion in a substrate or a semiconductor layer on the substrate, and then forming on an upper surface of the substrate or an upper surface of the semiconductor layer a nitride semiconductor multilayer film including an active layer that produces light during operation; and (b) forming in an upper part of the nitride semiconductor multilayer film a ridge stripe that has a front end facet and a rear end facet facing the front end facet and serves as an optical waveguide, wherein multiple ones of the recess, the stepped portion, or the protruding portion are provided discontinuously, and in the step (b), the ridge stripe is formed so that a distance from a lateral center of the ridge stripe to a lateral center of the recess, the stepped portion, or the protruding portion changes from the front end facet toward the rear end facet whereby bandgap energy of the active layer is changed continuously or in stages from the front end facet toward the rear end facet, and the ridge stripe is formed along the recesses, the stepped portions, or the protruding portions.