# US 2019/0378937 A1 · Focused energy photovoltaic cell > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0378937 A1 - Document ID: US20190378937A1 - Status: Published application - Kind: A1 - Application number: 16/547,860 - Filed: 2019-08-22 - Published: 2019-12-12 - Earliest claimed: 2017-05-03 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: Talia S. Gershon; Ning Li; Devendra K. Sadana; Ghavam G. Shahidi - Web page: https://patentgrep.com/patent/US20190378937A1 ## CPC - H10F 77/311: {for photovoltaic cells} - H10F 10/144: comprising only Group III-V materials, e.g. GaAs,AlGaAs, or InP photovoltaic cells - H10F 10/163: comprising only Group III-V materials, e.g. GaAs/AlGaAs or InP/GaInAs photovoltaic cells - H10F 71/127: {The active layers comprising only Group III-V materials, e.g. GaAs or InP} - H10F 71/139: {using temporary substrates} - Y02E 10/544: Solar cells from Group III-V materials - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A photovoltaic device that includes a p-n junction of first type III-V semiconductor material layers, and a window layer of a second type III-V semiconductor material on the light receiving end of the p-n junction, wherein the second type III-V semiconductor material has a greater band gap than the first type III-V semiconductor material, and the window layer of the photovoltaic device has a cross-sectional area of microscale. ## Claims ### Claim 1 A photovoltaic device comprising: a p-n junction of first type III-V semiconductor material layers; and a window bilayer of a second type III-V semiconductor material on a light receiving end of the p-n junction and a transparent dielectric layer present on the second type III-V semiconductor material layer, wherein the second type III-V semiconductor material layer has a greater band gap than the first type III-V semiconductor material, and the window bilayer of the photovoltaic device has a cross-sectional area of microscale. ### Claim 2 (depends on 1) The photovoltaic device of claim 1, wherein the p-n junction of the first type III-V semiconductor material layer has an emitter layer comprised of a first gallium and arsenic containing layer doped to a first conductivity type that is in direct contact with the window layer; and a base layer on an opposite side of the emitter layer that is contact with the window layer, the base layer comprised of a second gallium and arsenic containing layer having a second conductivity type. ### Claim 3 (depends on 2) The photovoltaic device of claim 2, wherein the first gallium and arsenic containing layer has a nanoscale thickness, and the second gallium and arsenic containing layer has a microscale thickness. ### Claim 4 (depends on 1) The photovoltaic device of claim 1, further comprising electrodes of a type III-V semiconductor material on opposing ends of said window layer. ### Claim 5 (depends on 1) The photovoltaic device of claim 1, further comprising a supporting substrate that is present underlying the p-n junction, wherein the supporting substrate is separated from the base layer by a back surface filed layer composed of indium gallium phosphide or aluminum gallium arsenide. ### Claim 6 (depends on 1) The photovoltaic device of claim 1, wherein the second type III-V semiconductor material of the window bilayer is comprised of indium gallium phosphide or aluminum gallium arsenide having a thickness ranging from 200 nm to 1 micron; and the transparent conductive oxide is composed of zinc oxide having a thickness ranging from 500 nm to 5 microns. ### Claim 7 (depends on 1) The photovoltaic device of claim 1, wherein the photovoltaic device generates power ranging from the microwatt (μW) to milliwatt (mW) within a chip area of 100 μm×100 μm. ### Claim 8 A method of forming a photovoltaic device comprising: forming a p-n junction of type III-V semiconductor material layer having a microscale footprint on a supporting substrate; and forming a window layer on the light receiving end of the p-n junction, the window layer has a cross-sectional area of a microscale. ### Claim 9 (depends on 8) The method of claim 8, wherein the window layer comprises a single material layer having of a type III-V semiconductor material lay having a greater band gap than the type III-V semiconductor material layer of the p-n junction. ### Claim 10 (depends on 9) The method of claim 9, wherein the window layer comprises of indium gallium phosphide or aluminum gallium arsenide having a thickness ranging from 500 nm to 5 microns. ### Claim 11 (depends on 9) The method of claim 9, wherein the window layer is a bilayer comprising a single material layer having of a type III-V semiconductor material layer having a greater band gap than the type III-V semiconductor material layer of the p-n junction, and a transparent dielectric layer. ### Claim 12 (depends on 11) The method of claim 11, wherein the type III-V semiconductor material of the window bilayer is comprised of indium gallium phosphide or aluminum gallium arsenide having a thickness ranging from 200 nm to 1 micron; and the transparent dielectric layer is composed of zinc oxide having a thickness ranging from 100 nm to 5 microns. ### Claim 13 (depends on 12) The method of claim 12, wherein photovoltaic device generates power ranging from a microwatt (μW) to a milliwatt (mW) within a chip area of 100 μm×100 μm using focused light or laser light. ### Claim 14 A photovoltaic device comprising: a p-n junction formed between an emitter layer and a base layer of first type III-V semiconductor material layers; and a window bilayer of a second type III-V semiconductor material on a light receiving end of the p-n junction and a transparent dielectric layer present on the second type III-V semiconductor material layer, the window bilayer of the photovoltaic device has a thickness greater than a thickness of the base layer. ### Claim 15 (depends on 14) The photovoltaic device of claim 14, wherein the emitter layer includes a first gallium and arsenic containing layer doped to a first conductivity type that is in direct contact with the window layer; and the base layer on an opposite side of the emitter layer that is contact with the window layer, the base layer including a second gallium and arsenic containing layer having a second conductivity type. ### Claim 16 (depends on 15) The photovoltaic device of claim 15, wherein the first gallium and arsenic containing layer has a nanoscale thickness, and the second gallium and arsenic containing layer has a microscale thickness. ### Claim 17 (depends on 14) The photovoltaic device of claim 14, further comprising electrodes of a type III-V semiconductor material on opposing ends of said window layer. ### Claim 18 (depends on 14) The photovoltaic device of claim 14, further comprising a supporting substrate that is present underlying the p-n junction, wherein the supporting substrate is separated from the base layer by a back surface filed layer composed of indium gallium phosphide or aluminum gallium arsenide. ### Claim 19 (depends on 14) The photovoltaic device of claim 14, wherein the second type III-V semiconductor material of the window bilayer is comprised of indium gallium phosphide or aluminum gallium arsenide having a thickness ranging from 200 nm to 1 micron; and the transparent conductive oxide is composed of zinc oxide having a thickness ranging from 500 nm to 5 microns. ### Claim 20 (depends on 14) The photovoltaic device of claim 14, wherein the photovoltaic device generates power ranging from the microwatt (μW) to milliwatt (mW) within a chip area of 100 μm×100 μm.