LAUSR

GeSn alloys have the potential of extending the Si photonics functionality in short-wave infrared (SWIR) light emission and detection. Epitaxial GeSn layers were deposited on a relaxed Ge buffer on Si(100) wafer by using high power impulse magnetron sputtering (HiPI-MS). Detailed X-ray reciprocal space mapping and HRTEM investigations indicate higher crystalline quality of GeSn epitaxial layers deposited by Ge HiPI-MS in respect to commonly used radio frequency magnetron sputtering (RF-MS). To obtain a rectifying heterostructure for SWIR light detection, a layer of GeSn nanocrystals (NCs) embedded in oxide was deposited on the epitaxial GeSn one. Embedded GeSn NCs are obtained by co-sputtering deposition of (Ge1-xSnx)1-y(SiO2)y layers and subsequent rapid thermal annealing at a low temperature of 400oC. Intrinsic GeSn structural defects give p-type behaviour, while the oxygen presence leads to the n-character of the embedded GeSn NCs. Such embedded NCs/epitaxial GeSn p-n heterostructure shows superior photoelectrical response up to three orders of magnitude increase in the 1.2-2.5 µm range, as compared to performances of diode based only on embedded NCs.