Locally strained Ge/SOI structures with improved heat sink as an active media for silicon optoelectronics

In this work formation of locally strained Ge structures on SOI substrates is reported and their optical properties are discussed. Suspended Ge structures were fabricated by optical lithography, plasmachemical and wet chemical etching using the “stress concentration” approach. The fabrication procedure of suspended structures were modified in such a way to provide the mechanical contact between them and the underlying layers so improving the heat dissipation from them. SOI substrates with top Si layer being only 100 nm thick were utilized in such fabrication scheme. The decrease of local heating in such kind of structures was confirmed by the study of micro-Raman scattering depending of scanning laser power. Micro-photoluminescence measurements have shown the remarkable enhancement of the integrated intensity from locally strained areas of a microstructure. It was also shown that structures brought in contact with underlying layers could sustain much higher pumping power densities without fracture as compared to the suspended ones.