Date Published: March 27, 2018
Publisher: John Wiley and Sons Inc.
Author(s): Nils von den Driesch, Daniela Stange, Denis Rainko, Ivan Povstugar, Peter Zaumseil, Giovanni Capellini, Thomas Schröder, Thibaud Denneulin, Zoran Ikonic, Jean‐Michel Hartmann, Hans Sigg, Siegfried Mantl, Detlev Grützmacher, Dan Buca.
Growth and characterization of advanced group IV semiconductor materials with CMOS‐compatible applications are demonstrated, both in photonics. The investigated GeSn/SiGeSn heterostructures combine direct bandgap GeSn active layers with indirect gap ternary SiGeSn claddings, a design proven its worth already decades ago in the III–V material system. Different types of double heterostructures and multi‐quantum wells (MQWs) are epitaxially grown with varying well thicknesses and barriers. The retaining high material quality of those complex structures is probed by advanced characterization methods, such as atom probe tomography and dark‐field electron holography to extract composition parameters and strain, used further for band structure calculations. Special emphasis is put on the impact of carrier confinement and quantization effects, evaluated by photoluminescence and validated by theoretical calculations. As shown, particularly MQW heterostructures promise the highest potential for efficient next generation complementary metal‐oxide‐semiconductor (CMOS)‐compatible group IV lasers.
Epitaxy: All investigated layers were produced by means of chemical vapor deposition (CVD) in an industry‐compatible reactor design on 200 mm wafers. The employed precursors disilane (Si2H6), digermane (Ge2H6), and tin tetrachloride (SnCl4) ensure high growth rates (typically 15–20 nm min−1) at low growth temperatures (between 350 and 360 °C), helpful for suppression of quality‐degrading Sn precipitates and surface segregation. To reduce the large lattice mismatch between the Si (001) and the (Si)GeSn alloys, growth was performed on top of around 2.5 µm thick Ge–VS.33 Prior to the growth, the native oxide was removed in an automated single‐wafer cleaning tool using hydrofluoric acid vapor chemistry, followed by an in situ hydrogen bake.
The authors declare no conflict of interest.