Strained germanium light emitting diodes with microbridge based on edge stress concentration

Ge has become a focus in the development of optoelectronic devices integrated into silicon platforms due to its compatibility with standard complementary metal-oxide-semiconductor (CMOS) technology. To reduce the bandgap of Ge, thereby enhancing its optical properties and accelerating the development of CMOS-compatible silicon-based germanium light sources, we propose a strained Ge LED with a microbridge structure. By etching two isosceles triangles with opposite apexes on the Ge layer and utilizing the edge stress concentration, the ideal tensile strain is achieved at the edge of the microbridge. Simulation results show that the Ge LED exhibits a peak wavelength of 1960 nm and a maximum electrical-to-optical conversion efficiency of 1.6%. Finally, this single structure is expanded into a ring-shaped array to increase the area of stress concentration. Simulation results show that the Ge LED array exhibits a peak wavelength of 1790 nm and a maximum electrical-to-optical conversion efficiency of 1.45%.