Tensile strain of germanium micro-disks on freestanding SiO2 beams

Abstract

Tensile strain is crucial to expect the direct recombination in germanium (Ge), towards monolithic light sources on silicon (Si). Freestanding beams of Ge are known to produce strong tensile strain, however, it is not trivial to construct a cavity in a freestanding structure. Here, we fabricated Ge micro-disks on freestanding oxide beams, and observed Whispering-Gallery-Modes (WGM) by photoluminescence. The tensile strain was larger in shorter beams, which is consistent with simulations