# US 2025/0147235 A1 · Photodetectors with a notched light-absorbing layer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0147235 A1 - Document ID: US20250147235A1 - Status: Published application - Kind: A1 - Application number: 18/501,602 - Filed: 2023-11-03 - Published: 2025-05-08 - Earliest claimed: 2023-11-03 - Assignees: GlobalFoundries U.S. Inc. - Applicants: GlobalFoundries U.S. Inc. - Inventors: Yusheng Bian; Andreas D. Stricker; Abdelsalam Aboketaf; Judson R. Holt; Kevin K. Dezfulian; Kenneth J. Giewont; Alexander Derrickson; Won Suk Lee; Sujith Chandran; Ryan W. Sporer; Teng-Yin Lin - Web page: https://patentgrep.com/patent/US20250147235A1 ## CPC - G02B 6/12004: {Combinations of two or more optical elements} - G02B 6/1228: {Tapered waveguides, e.g. integrated spot-size transformers (for coupling with fibres G02B6/305)} - G02B 6/13: Integrated optical circuits characterised by the manufacturing method - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract Structures for a photonics chip that include a photodetector and methods of forming such structures. The structure comprises a photodetector that is disposed on a substrate and that includes a light-absorbing layer. The light-absorbing layer includes a sidewall and a notch in the sidewall. The structure further comprises a waveguide core including a section adjacent to the notch in the sidewall of the light-absorbing layer. ## Claims ### Claim 1 A structure for a photonics chip, the structure comprising: a substrate; a photodetector on the substrate, the photodetector including a light-absorbing layer, and the light-absorbing layer including a first sidewall and a first notch in the first sidewall; and a first waveguide core including a section adjacent to the first notch in the first sidewall of the light-absorbing layer. ### Claim 2 (depends on 1) The structure of claim 1 wherein the section of the first waveguide core is tapered with a width dimension that increases with decreasing distance from the first sidewall of the light-absorbing layer. ### Claim 3 (depends on 1) The structure of claim 1 wherein the light-absorbing layer includes a longitudinal axis, and the first notch is centered along the first sidewall relative to the longitudinal axis. ### Claim 4 (depends on 1) The structure of claim 1 wherein the light-absorbing layer includes a longitudinal axis, and the section of the first waveguide core includes a longitudinal axis that is aligned with the longitudinal axis of the light-absorbing layer. ### Claim 5 (depends on 1) The structure of claim 1 wherein the light-absorbing layer includes a longitudinal axis, and the section of the first waveguide core includes a longitudinal axis that is aligned at an acute angle relative to the longitudinal axis of the light-absorbing layer. ### Claim 6 (depends on 1) The structure of claim 1 wherein the light-absorbing layer includes a longitudinal axis, a second sidewall, and a third sidewall, and the first notch is positioned between the second sidewall and the third sidewall. ### Claim 7 (depends on 6) The structure of claim 6 wherein the second sidewall and the third sidewall are angled at respective acute angles relative to the longitudinal axis. ### Claim 8 (depends on 7) The structure of claim 7 wherein the second sidewall and the third sidewall are outwardly curved. ### Claim 9 (depends on 8) The structure of claim 8 wherein the second sidewall meets the third sidewall at a cusp. ### Claim 10 (depends on 7) The structure of claim 7 wherein the second sidewall and the third sidewall are inwardly curved. ### Claim 11 (depends on 1) The structure of claim 1 wherein the light-absorbing layer includes a longitudinal axis, a second sidewall, and a second notch in the second sidewall, the second notch is spaced along the longitudinal axis from the first notch, and further comprising: a second waveguide core including a section adjacent to the second notch in the second sidewall of the light-absorbing layer. ### Claim 12 (depends on 11) The structure of claim 11 wherein the section of the first waveguide core has a longitudinal axis that is aligned with the longitudinal axis of the light-absorbing layer, and the section of the second waveguide core has a longitudinal axis that is aligned with the longitudinal axis of the light-absorbing layer. ### Claim 13 (depends on 11) The structure of claim 11 wherein the section of the first waveguide core has a longitudinal axis that is aligned at an acute angle relative to the longitudinal axis of the light-absorbing layer, and the section of the second waveguide core has a longitudinal axis that is aligned at an acute angle relative to the longitudinal axis of the light-absorbing layer. ### Claim 14 (depends on 1) The structure of claim 1 further comprising: a pad connected to the section of the first waveguide core; a first doped region in the pad, the first doped region having a first conductivity type; and a second doped region in the pad, the second doped region having a second conductivity type opposite to the first conductivity type, wherein the light-absorbing layer is disposed on a portion of the pad between the first doped region and the second doped region, and the portion of the pad comprises intrinsic semiconductor material. ### Claim 15 (depends on 1) The structure of claim 1 wherein the first notch is a concavity having a second sidewall that is curved. ### Claim 16 (depends on 1) The structure of claim 1 wherein the first notch penetrates through a full thickness of the light-absorbing layer. ### Claim 17 (depends on 1) The structure of claim 1 wherein the first notch opens toward the section of the first waveguide core. ### Claim 18 (depends on 1) The structure of claim 1 wherein the light-absorbing layer includes a second sidewall and a third sidewall, the first sidewall includes a first portion between the first notch and the second sidewall, and the first sidewall includes a second portion between the first notch and the third sidewall. ### Claim 19 (depends on 18) The structure of claim 18 wherein the light-absorbing layer includes a first prong between the first notch and the second sidewall, and the light-absorbing layer includes a second prong between the first notch and the third sidewall. ### Claim 20 A method of forming a structure for a photonics chip, the method comprising: forming a photodetector on a substrate, wherein the photodetector includes a light-absorbing layer, and the light-absorbing layer includes a sidewall and a notch in the sidewall; and forming a waveguide core including a section adjacent to the notch in the sidewall of the light-absorbing layer.