Bandgap technology and process development for genetic InP monolithic integration

Abstract

The increasing complexity of next-generation optical communications systems and networking architectures requires more components to be integrated on a single chip, forming photonic integrated circuits (PICs), in order to enhance the performance and reliability, and increase the functionality while lowering the manufacturing cost. These benefits are similar to what has been achieved in very large scale integrated circuits (VLSI) in the electronics industry. Quantum well/dot intermixing (QWI/QDI), a post-growth process for tuning the bandgap of a semiconductor epilayer in selective areas as required by specific devices, is a key technology to enabling PIC fabrication due to its relative simplicity compared to other technologies such as selective area growth, growth-regrowth, etc. In this project, argon plasma enhanced QWI/QDI, a technique invented by us, is investigated as the enabling technology for photonic integration application. InP and InGaAs cap layers with different doping types were investigated with polarized edge- emitting photoluminescence analysis technique. A theoretical model was built up to quantitatively analyze QWI. The derived diffusion lengths on group V and III sublattices show that the cap material plays an important role as it influences both the accumulation and diffusion of point defects during plasma process and annealing process, respectively. It is showed that the p-InP is a suitable cap material for realizing large blue shift for photonic integration application. The influence of plasma process on p-InP cap material for blue shift application is also investigated. The results show that the high rf power during argon plasma process is suitable for achieving maximum blue shift, whereas the low rf power is more controllable. The application of Ar-plasma enhance QWI on photonic integration is investigated on an optimized full structure with a p-InP sacrificial layer. Integrated superluminescent diode and integrated multi-mode interferometer with semiconductor optical amplifier are presented to demonstrate the Ar-plasma enhanced QWI for photonic integration application.