Am Dienstag den 22. Januar setzt sich das IHT-Kolloquium fort, es spricht:
Materials Research Department
IHP - Leibniz-Institut für innovative Mikroelektronik (IHP GmbH)
Frankfurt (Oder), Deutschland
„Optoelectronics Based on GeSn Nanostructures”
The incorporation of tin (Sn) into germanium (Ge) provides the opportunity to engineer the energy band structure of elemental semiconductors, making group IV materials suitable for CMOS-compatible Si photonic applications, such as potential GeSn-based laser and photodetectors. The key aspect towards high performance optoelectronics is the formation of high-quality GeSn/Si nanostructures, avoiding Sn precipitation caused by the limited solid miscibility of Sn into Ge (< 1 %) as well as the introduction of extended defects, due to the lattice and thermal mismatch between island and substrate. In our studies, we demonstrate the selective molecular beam (MBE) epitaxy of GeSn islands on nano patterned Si wafers by exploiting the nanoheteroepitaxy (NHE) approach at relatively high growth temperatures, exceeding the eutectic temperature of Tec ≈ 231 °C. While carefully controlling the Sn atom migration, the obtained alloys exhibit a Sn contents of potential interest for the realization of integrated photodetectors with high absorption in the spectral region of the telecommunication L and U band, i.e. beyond the 1550 nm limit featured by Ge-based devices. A first demonstration of a Ge(Sn) based photodetctor was successful, coupling the light into the islands by plasmonic field enhancement caused by self aligned Al nano antennas.