Title: Self-Organized Ge Quantum Dots for Si Photonics on SiN platforms

Date: 18th September 2023, Monday

Time: 11:00 am (Central European Time)

Host: Prof. Konrad Banaszek

The seminar will be in the CeNT aula hall (00.142) on the main floor.

Abstract:

Since the inception of the first transistors in the 1940s, the enormous investment and immense body of research on Group IV semiconductors, including silicon (Si) and germanium (Ge), have spearheaded spectacular and rapid advances in ULSI technology enabling a vast landscape of applications including logic, memory, computing, and sensing, etc. Although Ge was the initial semiconductor of choice for both research and industry, it was quickly superseded by Si as the active-layer material of choice for both bipolar junction transistors and MOSFETs. However, more recently, Ge-based nanoelectronics is making a comeback. In particular, Ge nanophotonics is breaking new ground as the enabling technology for Si photonics applications.

Starting with our exciting discovery of Ge spherical quantum dot (QD) formation via the peculiar and symbiotic interactions of Si, Ge and O interstitials, we have embarked on an exciting journey of vigorous exploration, creating unique configurations of self-organized Ge QDs/Si-containing layers. Our aim is to generate advanced Ge QD photonic active devices, while using standard, mainstream Si processing techniques. This talk summarizes our portfolio of innovative Ge QD configurations. With emphasis on both controllability and repeatability, we have fabricated size-tunable, spherical Ge QDs that are placed at predetermined spatial locations within Si-containing layers (SiO2, Si3N4, and Si) using a coordinated combination of lithographic patterning and self-assembled growth. A significant fabrication advantage of our approach is the high-temperature thermal stability of Ge QDs that are formed by thermal oxidation of poly-SiGe at 900 oC, offering process flexibility in the waveguide-material choices and device designs. Our Ge QD configurations have allowed a myriad of integration possibilities including top-to-bottom evanescent-wave coupling structures for SiN-waveguided Ge-QD photodetectors and Ge-QD light-emitters within Si3N4 integrated photonics platforms for on-chip interconnects and sensing.