SAE of Ge and GeSn Nanowires for Photonic Applications on Si Platform

While microelectronics is dominated by silicon platform as well as in photonics in the so-called silicon photonics. In the latter context, Si is used for waveguiding. The indirect nature of the bandgap renders it unsuitable for light emission. To further expand this platform, a semiconductor active in the telecommunication wavelengths is still needed. GeSn is a promising material enabling monolithic silicon photonics in the NIR and in particular at telecommunication wavelengths [1].

In this work, we demonstrate the few approaches to achieve components of a (Si)GeSn photonic integrated circuit: selective area growth of Ge NWs as waveguides, study of p- and n-doped growth of Ge NWs for photodetector fabrication, and GeSn as an emitter in the NIR.

The in-plane Ge NWs are grown selectively on Si (100) by metal organic vapor phase epitaxy (MOVPE). We show control on the crystal quality and shape. NWs with well-defined facet morphology are obtained along the crystallographic orientations <110> and <100> [2][3]. We extended this knowledge and technique to the MOVPE growth of doped Ge NWs, adding Ga and As for p- and n-doped, respectively

GeSn thin films are obtained by magnetron sputtering in a coaxial configuration on Si (100). We report on the optimization of the growth parameters for the achievement of GeSn thin films of different Sn contents. The optimized parameters are used for the fabrication of GeSn NWs by a top-down approach. The GeSn properties are evaluated by x-ray diffraction (XRD), atomic force microscopy (AFM), and Raman spectroscopy. The study of the Sn content and its segregation is studied looking at the cross section by energy dispersive x-ray analysis (EDX) and transmission electron microscopy (TEM).