# US 7,745,900 B2 · Method and apparatus providing refractive index structure for a device capturing or displaying images > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,745,900 B2 - Document ID: US7745900B2 - Status: Granted - Kind: B2 - Application number: 11/209,752 - Filed: 2005-08-24 - Published: 2007-03-01 - Granted: 2010-06-29 - Earliest claimed: 2005-08-24 - Assignees: Micron Technology, Inc. - Inventors: Jiutao Li; Jin Li - Web page: https://patentgrep.com/patent/US7745900B2 ## CPC - G02B 1/115: Multilayers - G02B 1/11: Anti-reflection coatings - H10F 39/802: {Geometry or disposition of elements in pixels, e.g. address-lines or gate electrodes} - H10F 39/805: {Coatings} - Y10S 977/773: Nanoparticle, i.e. structure having three dimensions of 100 nm or less - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract A transient index stack having an intermediate transient index layer, for use in an imaging device or a display device, that reduces reflection between layers having different refractive indexes by making a gradual transition from one refractive index to another. Other embodiments include a pixel array in an imaging or display device, an imager system having improved optical characteristics for reception of light by photosensors and a display system having improved optical characteristics for transmission of light by photoemitters. Enhanced reception of light is achieved by reducing reflection between a photolayer, for example, a photosensor or photoemitter, and surrounding media by introducing an intermediate layer with a transient refractive index between the photolayer and surrounding media such that more photons reach the photolayer. The surrounding media can include a protective layer of optically transparent media. ## Claims ### Claim 1 An optical structure for an imaging device comprising: a photo device arranged in a first layer, and an associated optical path for the photo device, said optical path comprising: the first layer comprising a first material having a first refractive index; a second layer comprising a second material having a second refractive index; and a transition region comprising the first material and the second material and arranged between said first and second layers and having a refractive index which changes from a value at or about said first refractive index to a value at or about said second refractive index. ### Claim 2 (depends on 1) The optical structure according to claim 1, wherein said transition region comprises a mixture of said first and second materials; and wherein a ratio of said first material to said second material in said mixture increases in the direction of the optical path toward the second layer. ### Claim 3 (depends on 2) The optical structure according to claim 2, wherein the increase in the ratio of said first material to said second material in said mixture in the direction of the optical path is proportional to depth in the direction of the optical path toward the second layer. ### Claim 4 (depends on 1) The optical structure according to claim 1, wherein the transition region comprises quantum dots of said second material of a size less than 0.2 um within said first material. ### Claim 5 (depends on 1) The optical structure according to claim 1, wherein the transition region comprises a stack of discrete transition layers, each layer comprising a uniform mixture of said first and second materials. ### Claim 6 (depends on 5) The optical structure according to claim 5, wherein the ratio of said first material to said second material in each discrete transition layer increases incrementally in the direction of the second layer. ### Claim 7 (depends on 1) The optical structure according to claim 1, wherein the imaging device is adapted to capture an image and said photo device is a photosensor. ### Claim 8 (depends on 1) The optical structure according to claim 1, wherein the imaging device is adapted to display an image and said photo device is a photoemitter. ### Claim 9 An optical structure for an imaging device comprising: a photo device arranged in a first layer, and an associated optical path for the photo device, said optical path comprising: the first layer comprising a first material having a first refractive index; a second layer comprising a second material having a second refractive index; and a transition region comprising the first material and the second material and arranged between said first and second layers and having a refractive index which changes from a value at or about said first refractive index to a value at or about said second refractive index, wherein said transition region comprises a mixture of said first and second materials, wherein a ratio of said first material to said second material in said mixture increases in the direction of the optical path toward the second layer, and wherein said first material is silicon dioxide and said second material is silicon. ### Claim 10 (depends on 9) The optical structure according to claim 9, wherein said silicon is provided as a substrate for said photo device. ### Claim 11 (depends on 9) The optical structure according to claim 9, wherein the increase in the ratio of said first material to said second material in said mixture in the direction of the optical path is proportional to depth in the direction of the optical path toward the second layer. ### Claim 12 (depends on 9) The optical structure according to claim 9, wherein the imaging device is adapted to capture an image and said photo device is a photosensor. ### Claim 13 (depends on 9) The optical structure according to claim 9, wherein the imaging device is adapted to display an image and said photo device is a photoemitter. ### Claim 14 An imaging system comprising: a CPU; and an imaging device comprising an optical structure, said optical structure comprising: a photo device arranged in a first layer, and an associated optical path for the photo device, said optical path comprising: the first layer comprising a first material having a first refractive index; a second layer comprising a second material having a second refractive index; and a transition region comprising the first material and the second material and arranged between said first and second layers and having a refractive index which changes from a value at or about said first refractive index to a value at or about said second refractive index. ### Claim 15 (depends on 14) The system according to claim 14, wherein said transition region comprises a mixture of said first and second materials; and wherein a ratio of said first material to said second material in said mixture increases in the direction of the optical path toward the second layer. ### Claim 16 (depends on 15) The system according to claim 15, wherein the increase in the ratio of said first material to said second material in said mixture in the direction of the optical path is proportional to depth in the direction of the optical path toward the second layer. ### Claim 17 (depends on 14) The imaging system according to claim 14, wherein the transition region comprises quantum dots of said second material of a size less than 0.2 um within said first material. ### Claim 18 (depends on 14) The imaging system according to claim 14, wherein the transition region comprises a stack of discrete transition layers, each layer comprising a uniform mixture of said first and second materials. ### Claim 19 (depends on 18) The system according to claim 18, wherein the ratio of said first material to said second material in each discrete transition layer increases incrementally in the direction of the second layer. ### Claim 20 (depends on 14) The system according to claim 14, wherein the imaging device is adapted to capture an image and said photo device is a photosensor. ### Claim 21 (depends on 14) The system according to claim 14, wherein the imaging device is adapted to display an image and said photo device is a photoemitter. ### Claim 22 An imaging system comprising: a CPU; and an imaging device comprising an optical structure, said optical structure comprising: a photo device arranged in a first layer, and an associated optical path for the photo device, said optical path comprising: the first layer comprising a first material having a first refractive index; a second layer comprising a second material having a second refractive index; and a transition region comprising the first material and the second material and arranged between said first and second layers and having a refractive index which changes from a value at or about said first refractive index to a value at or about said second refractive index, wherein said transition region comprises a mixture of said first and second materials, wherein a ratio of said first material to said second material in said mixture increases in the direction of the optical path toward the second layer, and wherein said first material is silicon dioxide and said second material is silicon. ### Claim 23 (depends on 22) The system according to claim 22, wherein said silicon is provided as a substrate for said photo device. ### Claim 24 (depends on 22) The system according to claim 22, wherein the increase in the ratio of said first material to said second material in said mixture in the direction of the optical path is proportional to depth in the direction of the optical path toward the second layer. ### Claim 25 (depends on 22) The system according to claim 22, wherein the imaging device is adapted to capture an image and said photo device is a photosensor. ### Claim 26 (depends on 22) The system according to claim 22, wherein the imaging device is adapted to display an image and said photo device is a photoemitter.