“Recent progress in III-Vs on Si: From high-efficiency tandem solar cells to visible lasers”
III-V devices represent the gold standard for high performance and reliability in demanding applications that include high-speed optical and wireless communication, energy-efficient lighting, and space solar cells. Since III-V materials are so well-developed, one may ask what new questions remain to be answered? In this talk, I aim to provide some answers to this question by describing our efforts to expand the reach of III-V optoelectronics using an approach spanning from materials growth to device fabrication. In particular, we seek opportunities to significantly boost performance and functionality through integration of lattice-mismatched materials. In the first part of the talk, I will describe efforts in my group to marry the high efficiency of III-V solar cells with the low-cost manufacturing of silicon. Over the past several years, our research has enabled us to reduce the defect density in 1.7 eV GaAsP grown on Si, enabling us to set an efficiency record of 25% for GaAsP/Si tandem solar cells. Next, I will discuss our recent work on AlGaInP-based red lasers on Si, including the recent demonstration of dislocation-tolerant InP quantum dots. Integrating such visible lasers with the SiN photonics platform promises to enable visible integrated photonics on a Si chip with applications in quantum computing, sensing, and metrology.