CVD Epitaxial Growth of GeSn Opens a New Route for Advanced Sn-Based Logic and Photonics Devices

Interest in Sn-based semiconductors largely increased during the last decade (Fig. 1). If doubts remained in the early 2000´s on the hypothetical use of (Si)GeSn epitaxial layers in advanced technologies (mainly due to the low Sn solubility in Si and Ge and the associated reduced thermal stability of those alloys), recent publications from various groups provide today a much better feeling on the potential of those materials. First of all, the growth of GeSn layers with high Sn content was demonstrated by different techniques overruling their apparent thermodynamics limitations. Next, and especially very recently, Sn-based devices are showing up: GeSn MOSCAP, GeSn pMOSFET or GeSn photodetectors for instance. This paper reviews the deposition techniques and different integration schemes to implement GeSn in various technologies and highlights the potential benefits in logic and photonics devices.