Development of Heterogeneously Integrated Photodiodes and Schottky Diodes on Silicon Platforms

There is a growing need in semiconductor fabrication for a versatile technique to tightly integrate devices of different material systems on the same platform. This is more critical when it comes to photonic integrated circuits (PICs) as they typically rely on a multitude of different materials. State-of-the-art integration methods to solve this issue include transfer printing (TP), and selective heteroepitaxial growth and each comes with its own limitations. Here, I introduce a versatile technique based on multi-layer adhesive wafer bonding to integrate different group III-V material systems on a common silicon chip. In this context, I demonstrate the integration of two applicable devices of distinct epitaxial stack—namely, a GaAs Schottky diode and an InP photodiode—on the same substrate. As a proof of concept, I applied this integration and successfully realized an on-chip photonic radio frequency rectifier.

On the other hand, PICs, primarily developed for telecom wavelengths, face limitations when applied to shorter wavelengths due to the opacity of silicon-on-insulator (SOI) waveguides. Addressing the challenge of integrating the optical components for shorter wavelength applications, the second part of my research focuses on heterogeneous integration of AlGaAs/GaAs photodetectors (PDs) on a highly functional platform i.e. tantalum pentoxide, for applications in the visible spectrum for the first time. These PDs feature low dark current of 20 pA, more than 56% quantum efficiency (QE) between 635 nm and 780 nm wavelengths, and up to 17 GHz bandwidth. Open eye diagrams up to 12 Gbit/s were measured as well, only limited by our experimental setup.