Gesn Bonding Technology for Integrated Laser-on-Chip Photonics

Abstract

With the numerous recent demonstrations of germanium-tin (GeSn) semiconductor lasers, this material has become the strongest candidate for the realization of photonic-integrated circuits (PICs). However, the high defect density of this material often results in high lasing thresholds, making them undesirable for real-world applications. Furthermore, the low-thermal budget of high Sn content (>9 at.%) GeSn makes it exceptionally hard to grow onto other materials without introducing point defects. Herein, we present a novel method of directly combining GeSn with other materials through low-temperature wafer bonding. Through this technique, we can reduce the harmful high defect density and improve the lasing performance. To cater to the low thermal budget, we optimized the bonding processes which is critical in preventing Sn segregation to the surface. Through this method, we provide compelling evidence for the enhancement in photoluminescence in GeSn. Additionally, this technique can be extended to fabricate new material stacks, presenting unforeseen opportunities in other fields such as non-linear photonics.