# US 8,787,418 B2 · Emitting device with compositional and doping inhomogeneities in semiconductor layers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,787,418 B2 - Document ID: US8787418B2 - Status: Granted - Kind: B2 - Application number: 13/572,446 - Filed: 2012-08-10 - Published: 2014-03-06 - Granted: 2014-07-22 - Earliest claimed: 2011-08-11 - Assignees: Sensor Electronic Technology, Inc. - Applicants: Michael Shur; Maxim S. Shatalov; Alexander Dobrinsky; Remigijus Gaska; Jinwei Yang - Inventors: Michael Shur; Maxim S. Shatalov; Alexander Dobrinsky; Remigijus Gaska; Jinwei Yang - Web page: https://patentgrep.com/patent/US8787418B2 ## CPC - H10D 62/815: of structures having periodic or quasi-periodic potential variation, e.g. superlattices or multiple quantum wells [MQW] - B82Y 20/00: Nanooptics, e.g. quantum optics or photonic crystals - H01S 5/3216: {quantum well or superlattice cladding layers} - H01S 5/342: {containing short period superlattices [SPS]} - H10H 20/812: within the light-emitting regions, e.g. having quantum confinement structures - H10P 14/3416: {Nitrides} - H01S 5/0421: {characterised by the semiconducting contacting layers (electrodes H01S5/0425)} - H01S 5/34333: {with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser} - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES - 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 - H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 ## Abstract A device including one or more layers with lateral regions configured to facilitate the transmission of radiation through the layer and lateral regions configured to facilitate current flow through the layer is provided. The layer can comprise a short period superlattice, which includes barriers alternating with wells. In this case, the barriers can include both transparent regions, which are configured to reduce an amount of radiation that is absorbed in the layer, and higher conductive regions, which are configured to keep the voltage drop across the layer within a desired range. ## Claims ### Claim 1 A device comprising: a short period superlattice (SPSL) semiconductor layer comprising a plurality of barriers, wherein a composition of at least one barrier varies along lateral dimensions of the at least one barrier such that a lateral cross section of the at least one barrier includes: a set of transparent regions, each transparent region having a transmission coefficient for a target radiation wavelength, l, greater than or equal to approximately sixty percent, wherein the set of transparent regions are at least ten percent of an area of the lateral cross section of the at least one barrier; and a set of higher conductive regions occupying a sufficient area of the area of the lateral cross section of the at least one barrier and having an average resistance per unit area to a vertical current flow resulting in a total voltage drop across the SPSL of less than approximately five volts. ### Claim 2 (depends on 1) The device of claim 1, wherein the device is configured to emit radiation having a dominant wavelength equal to l , wherein l is within a range of approximately 210 and approximately 350 nanometers. ### Claim 3 (depends on 1) The device of claim 1, wherein the at least one barrier is formed of an AlxGa1-xN alloy, where x is a molar fraction of aluminum and where x is greater than approximately −0.0048l+1.83 for each transparent region. ### Claim 4 (depends on 3) The device of claim 3, wherein each of the set of higher conductive regions comprises a molar fraction of aluminum providing a band gap at least five percent smaller than a band gap of the set of transparent regions. ### Claim 5 (depends on 1) The device of claim 1, wherein the set of higher conductive regions occupy at least two percent of the area of the lateral cross section of the at least one barrier. ### Claim 6 (depends on 1) The device of claim 1, wherein the average resistance per unit area to the vertical current flow for the set of higher conductive areas is less than or equal to approximately 10−2 ohm·cm2. ### Claim 7 (depends on 1) The device of claim 1, wherein the transmission coefficient is greater than or equal to approximately eighty percent. ### Claim 8 (depends on 1) The device of claim 1, wherein the device is configured to operate as one of: a light emitting diode or a laser. ### Claim 9 (depends on 1) The device of claim 1, wherein the at least one barrier is formed of an GazInyAlxB1-x-y-zN alloy, where x, y, and z are molar fractions of aluminum, indium, and gallium, respectively, and wherein the at least one barrier includes inhomogeneities in at least one of: x, y, or z. ### Claim 10 (depends on 1) The device of claim 1, wherein the plurality of barriers alternate with a plurality of wells, and wherein each of the plurality of barriers and each of the plurality of wells has a thickness less than or equal to approximately five nanometers. ### Claim 11 (depends on 1) The device of claim 1, wherein the set of set of transparent regions and the set of higher conductive regions are formed using nano-scale inhomogeneities. ### Claim 12 (depends on 1) The device of claim 1, wherein a characteristic distance between two higher conductive regions in the set of higher conductive regions is less than a lateral current spreading length. ### Claim 13 A device comprising: a short period superlattice (SPSL) semiconductor layer comprising a plurality of barriers, wherein a lateral cross section of each barrier includes: a set of transparent regions, each transparent region having a transmission coefficient for a target radiation wavelength, l, greater than or equal to approximately sixty percent, wherein the set of transparent regions are at least ten percent of an area of the lateral cross section of the barrier; and a set of higher conductive regions occupying a sufficient area of the area of the lateral cross section of the barrier and having an average resistance per unit area to a vertical current flow resulting in a total voltage drop across the SPSL of less than approximately five volts. ### Claim 14 (depends on 13) The device of claim 13, wherein each barrier is formed of an AlxGa1-xN alloy, where x is a molar fraction of aluminum and where x is greater than approximately −0.0048l+1.83 for each transparent region. ### Claim 15 (depends on 13) The device of claim 13, wherein the set of transparent regions and the set of higher conductive regions are formed by a non-uniform barrier thickness of each barrier. ### Claim 16 (depends on 13) The device of claim 13, wherein the set of transparent regions and the set of higher conductive regions are formed by a non-uniform compositional distribution along the barrier thickness of each barrier. ### Claim 17 (depends on 13) The device of claim 13, wherein the set of transparent regions and the set of higher conductive regions are formed by a non-uniform doping distribution along the barrier thickness of each barrier. ### Claim 18 A method of fabricating a device comprising: forming a short period superlattice (SPSL) semiconductor layer comprising a plurality of barriers, wherein a lateral cross section of each barrier includes: a set of transparent regions, each transparent region having a transmission coefficient for a target radiation wavelength, l, greater than or equal to approximately sixty percent, wherein the set of transparent regions are at least ten percent of an area of the lateral cross section of the barrier; and a set of higher conductive regions occupying a sufficient area of the area of the lateral cross section of the barrier and having an average resistance per unit area to a vertical current flow resulting in a total voltage drop across the SPSL of less than approximately five volts. ### Claim 19 (depends on 18) The method of claim 18, wherein the forming includes forming each barrier of an AlxGa1-xN alloy, where x is a molar fraction of aluminum and where x is greater than approximately −0.0048l+1.83 for each transparent region. ### Claim 20 (depends on 18) The method of claim 18, wherein the forming includes forming the set of transparent regions and the set of higher conductive regions using a non-uniform barrier thickness of each barrier. ### Claim 21 (depends on 18) The method of claim 18, wherein the forming includes forming the set of transparent regions and the set of higher conductive regions using a non-uniform compositional distribution along the barrier thickness of each barrier. ### Claim 22 (depends on 18) The method of claim 18, wherein the forming includes forming the set of transparent regions and the set of higher conductive regions using a non-uniform doping distribution along the barrier thickness of each barrier. ### Claim 23 (depends on 18) The method of claim 18, further comprising forming an inhomogeneous layer, wherein the SPSL semiconductor layer is formed directly on the inhomogeneous layer, and wherein at least a portion of the forming the inhomogeneous layer is performed at an inhomogeneous growth temperature at least approximately two hundred degrees Celsius lower than a temperature for forming the SPSL semiconductor layer. ### Claim 24 (depends on 23) The method of claim 23, wherein forming the inhomogeneous layer includes: enabling three-dimensional islands to coalesce at the inhomogeneous growth temperature; and enabling two-dimensional growth around the islands at a growth temperature comparable to the temperature for forming the SPSL semiconductor layer.