Semiconductor Hetero-Nanowires on Silicon for Photonic Applications

Semiconductor nanowires (NWs) can be combined with CMOS compatible technologies and provide much promise for optimized field-effect-transistors, efficient delivery and detection of light, and also sensing with ultrahigh... [ view full abstract ]

Semiconductor nanowires (NWs) can be combined with CMOS compatible technologies and provide much promise for optimized field-effect-transistors, efficient delivery and detection of light, and also sensing with ultrahigh detectivity. This is made possible especially with sophisticated core shell hetero-NW geometries.

I will discuss the fabrication of complex Ga(In,Al)As(P) based core-shell NWs grown by molecular beam epitaxy on pre-patterned Si substrates. The light emission can be tuned from about 1.6 eV down to about 0.4 eV, depending on composition and NW diameter, thus covering also the wavelength regime for optical fiber communication. The luminescence efficiency is increased by several orders of magnitude when the nanowires are passivated with appropriate thin shells. In this way we have achieved optically pumped infrared lasing up to room temperature from individual GaAs-AlGaAs core shell NWs with remarkably low threshold pump power densities. Our results show that by carefully designing NW materials composition profile high performance III-V near infrared NW lasers can be directly grown on Si substrates and thus open a path towards infrared photonic applications on a Si platform.

This work was performed in close collaboration with Gregor Koblmüller and Jonathan Finley together with various PhD- and master students at the Walter Schottky Institute of TUM. We acknowledge financial support from the Deutsche Forschungsgemeinschaft via SFB 631, the cluster of excellence “Nanosystems Intiative Munich”, and the Focus group “Nanophotonics” of the TUM Institute for Advanced Study.