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Title: Scalable and High Performance Monolithic On-Chip Light Sources for Integrated Silicon Photonics
Abstract: Epitaxial grown III-V gain materials onto the Si photonics wafers is the most economical approach to obtain on-chip light sources. Leveraging the defect insensitive quantum dot (QD) active regions and the advanced defect management epi designs, we have demonstrated record-breaking performance and reliability in blanket heteroepitaxy devices grown on CMOS-compatible Si. However, thick buffer layers for defect reduction prevent the evanescent light coupling from the active region to the Si waveguides underneath. In order to solve this problem, we later have demonstrated the first electrically pumped QD lasers grown in narrow pockets by molecular beam epitaxy on patterned 300 mm Si photonic wafers in a butt-coupled configuration after identifying and solving the unique growth and fabrication challenges imposed by the template architecture. The material uniformity, especially the QD morphology, has a strong dependence on the pocket orientation with respect to the III-V crystal and the pocket widths. In order to ensure yield and scalability of the in-pocket devices at 300 mm scale, we concluded that all pockets must be aligned to the [1 1
0] direction of the III-V single crystal within the pockets. We have also confirmed that, both experimentally and theoretically, the narrow strip geometry of the in-pocket material provides another degree of freedom for stress and defect manipulation. Promises are made that the performance and the reliability of the in-pocket lasers would surpass the state-of-the-art epitaxial devices grown on planar Si substrates. The final piece of the puzzle for a fully monolithically integrated Si photonic circuit is on the horizon.
About the Speaker: Dr. Chen Shang received his B.S. degree in Materials Science and Engineering from Purdue University in May 2016 with a Distinguished Graduate Award, and the Ph.D. degree in Optoelectronics Materials from Prof. John Bowers group at University of California, Santa Barbara, in 2022. His main research focus is epitaxial growth of quantum dot lasers on Si for realizing monolithic integration of on-chip light source for silicon photonics with molecular beam epitaxy technique. He was awarded Tingye Li Innovation Prize in CLEO 2023 for his contribution. He is currently a Post-Doctoral Researcher affiliated with the Institute for Energy Efficiency at University of California Santa Barbara. Leveraging his expertise in synthesizing quantum dots with molecular beam epitaxy, Dr. Chen Shang also aim to develop a platform for scalable quantum dot single/polarization entangled photon sources for integrated quantum photonics.
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