Abstract
The binary alloy semiconductor Ge1−xSnx is a promising candidate for the monolithic integration of optoelectronic circuits on Si due to its reported direct bandgap at specific Sn concentration and strain. However, while the directness of Ge1−xSnx improves with increasing Sn concentration, compressive strain counteracts with this trend. Since too high Sn concentrations lead to high amount of crystal defects due to Sn segregation, the growth of strain relaxed Ge1−xSnx would allow a decreasing Sn concentration and therefore an increasing crystal quality at once. The key issue is the growth of strain relaxed virtual Ge1−xSnx substrates for the subsequent epitaxy of Ge1−xSnx device structures, which seems to be the biggest obstacle with molecular beam epitaxy (MBE) so far. In this work, we report the epitaxy of partially relaxed Ge 0.92 Sn 0.08 layers via reduced pressure chemical vapor deposition (RPCVD), which serve as virtual substrate for the consecutive MBE of Ge 0.92 Sn 0.08 diode structures. This consecutive epitaxy process requires an extensive surface cleaning sequence, which had to be developed first. The quality of the grown diode structures was verified using X-ray diffraction (XRD). Furthermore, diodes were fabricated and electrically characterized. We will show that our approach is promising for high quality Ge1−xSnx devices on Si.
Users
Please
log in to take part in the discussion (add own reviews or comments).