Low Temperature Plasma-Assisted Growth of Core-Shell GeSn Nanowires with 30% Sn

We report on the growth of Sn-catalyzed GeSn NWs having a GeSn core and a c-Ge shell during a germane plasma at substrate temperatures (TS) below the GeSn eutectic temperature (TE), containing an exceptional Sn concentration of 30 at.% in their core. The differences between the NWs produced at TS above and below TE of the GeSn alloy are highlighted. Two types of NW growth process are identified: the previously reported In-Plane Solid-Liquid-Solid (IPSLS) for TS ≥ TE, and a Plasma-Assisted IPSLS abbreviated as PA-IPSLS method taking place at TS < TE; the crucial role of the plasma in providing the energy necessary to melt the Sn catalyst at substrates temperatures lower than TE is discussed. The thermal activation window for each method is determined. The PA-IPSLS process is shown to provide an efficient strategy for growing crystalline GeSn NWs with a high Sn incorporation in a growth duration of less than 3 min.