Germanium photodetectors on Silicon-on-insulator grown with differential molecular beam epitaxy in silicon wells

In this paper we propose a method for growing fast Germanium pin photodetectors in pre-patterned areas on a Silicon-on-insulator substrate. The layers are deposited by means of molecular beam epitaxy and structured by chemical mechanical polishing. A comparison of the electrical and optical characteristics between a photodetector grown with the proposed method and a reference detector grown on a planar Silicon substrate is made indicating only minor differences.

Research highlights
► We successfully fabricated vertical Germanium pin photodetectors in Silicon wells by using differential molecular beam epitaxy and chemical mechanical polishing.
► As the electrical properties indicate, the grown layers have a good crystal quality and external cut-off frequencies of over 20 GHz are achieved.
► The measured broad spectral range and the energy of the direct band edge leads to the conclusion that the new process does not increase the strain in the active Germanium absorption layer compared to conventional fabricated detectors.