Fabrication of SiGe/Ge microbridges based on Ge-on-Si(1 1 0) and observation of resonant light emission

Abstract

Strained SiGe/Ge microbridges are fabricated based on Ge-on-Si(110). The Si(110) substrate is employed to fabricate the microbridge along [111] direction as uniaxial strain in the [111] direction is expected to be the most effective to shift the direct valley of the conduction band. As a result, very strong room temperature photoluminescence is obtained from the fabricated Ge microbridge. It is remarkable that Fabry-Perot resonant peaks are seen in this emission, which is attributed to the vertical side wall of the bridge realized by the anisotropic dry etching process. Moreover, for the purpose of controlling of the emission wavelength, a SiGe layer is regrown on the Ge microbridge. We observe strong emissions from the SiGe at shorter wavelength, demonstrating that the emission wavelength can be controlled using SiGe/Ge hetero structures on the microbridge and this structure is very promising for realization of efficient light sources for Si photonics.