# US 7,745,841 B2 · Semiconductor light-emitting device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,745,841 B2 - Document ID: US7745841B2 - Status: Granted - Kind: B2 - Application number: 11/269,626 - Filed: 2005-11-09 - Published: 2006-05-11 - Granted: 2010-06-29 - Earliest claimed: 2004-11-10 - Assignees: Mitsubishi Denki Kabushiki Kaisha - Inventors: Kyosuke Kuramoto - Web page: https://patentgrep.com/patent/US7745841B2 ## CPC - H01S 5/22: having a ridge or stripe structure - B82Y 20/00: Nanooptics, e.g. quantum optics or photonic crystals - H01S 5/34333: {with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser} - H01S 5/2009: {by using electron barrier layers} - H01S 5/3407: {characterised by special barrier layers} - H01S 5/3415: {containing details related to carrier capture times into wells or barriers} - H10H 20/812: within the light-emitting regions, e.g. having quantum confinement structures - 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 - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES - H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS ## Abstract A semiconductor light-emitting device which exhibits small threshold current, high differential efficiency, and good characteristics, by reducing electrons that overflow an electron barrier, trapping the electrons in an active layer. Of the barrier layers of an active layer, a final barrier layer, which is a barrier layer closest to a p side, is smaller in band gap energy than other barrier layers. Thus, as compared with a case where the final barrier layer has the same band gap energy as that of the other barrier layer, an energy band discontinuity (electron barrier) with an electron blocking layer can be made larger. As a result, overflow of electrons is reduced. ## Claims ### Claim 1 A semiconductor light-emitting device comprising: an n-type cladding layer and a p-type cladding layer of a nitride-based III-V compound semiconductor material; an active layer, sandwiched by said n-type and p-type cladding layers, of a nitride-based III-V compound semiconductor material, wherein said active layer includes a plurality of barrier layers, and a plurality of well layers, said well and barrier layers being alternatingly arranged, all of said well layers of said active layer have a first bandgap energy that is substantially uniform, all of said barrier layers of said active layer have a second bandgap energy that is substantially uniform, and said active layer has a first end closer to said n-type cladding layer than to said p-type cladding layer, located adjacent one of said barrier layers, and a second end, closer to said p-type cladding layer than to said n-type cladding layer, and located adjacent one of said well layers; a final barrier layer of a nitride-based III-V compound semiconductor material, which, with said active layer, constitutes a multiple quantum well structure, and which is located between the second end of said active layer and said p-type cladding layer, said final barrier layer including at least one layer having a band gap energy that is smaller than the second band gap energy; and an electron blocking layer of a nitride-based III-V compound semiconductor material including Al and which is located between said final barrier layer and said p-type cladding layer, and which contacts said at least one layer of said final barrier layer having a band gap energy that is smaller than the second band gap energy, wherein said p-type cladding layer has a bandgap energy larger than the second bandgap energy, and said electron blocking layer has a bandgap energy larger than the bandgap energy of said p-type cladding layer. ### Claim 2 (depends on 1) The semiconductor light-emitting device according to claim 1, wherein the band gap energy of said final barrier layer becomes continuously smaller approaching said p-type cladding layer. ### Claim 3 (depends on 1) The semiconductor light-emitting device according to claim 1, wherein said barrier layers are InAlGaN. ### Claim 4 (depends on 1) The semiconductor light-emitting device according to claim 1, wherein said barrier layers are GaN. ### Claim 5 (depends on 1) The semiconductor light-emitting device according to claim 1, wherein said final barrier layer is InGaN, and said barrier layers are GaN. ### Claim 6 (depends on 1) The semiconductor light-emitting device according to claim 1, wherein said final barrier layer includes first and second layers, and, said second layer of said final barrier layer is closer to said p-type cladding layer than is said first layer, and said second layer has the band gap energy that is smaller than the second band gap energy. ### Claim 7 (depends on 6) The semiconductor light-emitting device according to claim 6, wherein said first layer of said final barrier layer is in contact with the second end of said active layer and has the second band gap energy. ### Claim 8 (depends on 1) The semiconductor light-emitting device according to claim 1, wherein said final barrier layer includes first and second layers, and said second layer of said final barrier layer is closer to said p-type cladding layer than is said first layer, and said second layer has a band gap energy that is smaller than the band gap energy of said first layer of said final barrier layer. ### Claim 9 (depends on 8) The semiconductor light-emitting device according to claim 8, wherein said first layer of said final barrier layer has the second band gap energy. ### Claim 10 (depends on 8) The semiconductor light-emitting device according to claim 8, wherein said second layer of said final barrier layer is InGaN, and said first layer of said final barrier layer is InGaN or GaN and has a larger band gap energy than said second layer of said final barrier layer. ### Claim 11 A semiconductor light-emitting device comprising: an n-type cladding layer and a p-type cladding layer of a nitride-based III-V compound semiconductor material; an active layer, sandwiched by said n-type and p-type cladding layers, of a nitride-based III-V semiconductor material, wherein said active layer includes a plurality of barrier layers, and a plurality of well layers alternating with said barrier layers, all of said well layers of said active layer have a first bandgap energy that is substantially uniform, all of said barrier layers of said active layer have a second bandgap energy that is substantially uniform, and said active layer has a first end closer to said n-type cladding layer than to said p-type cladding layer, located adjacent one of said barrier layers, and a second end, closer to said p-type cladding layer than to said n-type cladding layer, and located adjacent one of said well layers; a first layer of a of a nitride-based III-V compound semiconductor material which is located between the second end of said active layer and said p-type cladding layer, and which has a band gap energy smaller than the second band gap energy and larger than the first band gap energy; and an electron blocking layer of a nitride-based III-V compound semiconductor material including Al and which is located between said first layer and said p-type cladding layer, contacting said first layer, wherein said p-type cladding layer has a bandgap energy larger than the second bandgap energy, and said electron blocking layer has a bandgap energy larger than the bandgap energy of said p-type cladding layer. ### Claim 12 (depends on 11) The semiconductor light-emitting device according to claim 11, further comprising an optical waveguide layer having a larger band gap energy than the second band gap energy and disposed in contact with said p-type cladding layer, wherein said first layer is disposed between said active layer and said optical waveguide layer, in contact with said optical waveguide layer. ### Claim 13 (depends on 11) The semiconductor light-emitting device according to claim 11, wherein said electron blocking layer has a larger band gap energy than the second band gap energy, and said first layer is in contact with said electron blocking layer. ### Claim 14 (depends on 11) The semiconductor light-emitting device according to claim 11, wherein said first layer is in contact with the one of said well layers that is located at the second end of said active layer. ### Claim 15 (depends on 11) The semiconductor light-emitting device according to claim 11, wherein said plurality of barrier layers are InxAlyGa1-x-yN (0≦x<1, 0≦y<1, x+y≦1). ### Claim 16 (depends on 11) The semiconductor light-emitting device according to claim 11, further comprising a second layer disposed between said active layer and said first layer, in contact with said first layer, and having a band gap energy different from the band gap energy of said first layer and larger than the first band gap energy. ### Claim 17 (depends on 16) The semiconductor light-emitting device according to claim 16, wherein said second layer has the second band gap energy. ### Claim 18 (depends on 11) The semiconductor light-emitting device according to claim 11, wherein said barrier layers are GaN, and said first layer is InGaN. ### Claim 19 (depends on 18) The semiconductor light-emitting device according to claim 18, wherein said first layer has a thickness different from thicknesses of said plurality of barrier layers and said plurality of well layers. ### Claim 20 (depends on 18) The semiconductor light-emitting device according to claim 18, wherein said first layer is thicker than said plurality of barrier layers. ### Claim 21 (depends on 13) The semiconductor light-emitting device according to claim 13, wherein said barrier layers are InxGa1-xN, said well layers are InyGa1-yN, said first layer is InzGa1-zN, and In composition ratios x, y, and z satisfy 0(z−x). ### Claim 23 (depends on 21) The semiconductor light-emitting device according to claim 21, wherein said first layer has a thickness different from thicknesses of said plurality of barrier layers and said plurality of well layers. ### Claim 24 (depends on 21) The semiconductor light-emitting device according to claim 21, wherein said first layer is thicker than said plurality of barrier layers.