[Zurück]

S. Barth, M. Seifner, P. Pertl:
"Synthesis of Ge1-xSnx nanowires using molecular sources";
Vortrag: EMRS Spring Meeting, Lille; 02.05.2016 - 06.05.2016; in: "EMRS Spring Meeting 2016", (2016).

Group IV semiconductor nanowires are interesting building blocks for electronic and optoelectronic devices. However, the light emission and absorption characteristics can change dramatically, when a heavier homologue is incorporated in the crystal structure. Germanium can be converted in a tuneable narrow direct bandgap material by alloying with Sn to form a metastable Ge1−xSnx phase. This metastable group IV alloy can be used for band structure engineering by varying the tin content. Ge1−xSnx alloys are usually formed in gas phase processes taking advantage of homo- or heteroepitaxy between the growing layer and the substrate. The transition from an indirect to a direct bandgap was demonstrated for tin contents of approx. 11 % , which is far above the equilibrium solubility of Sn in Ge (<1%).
This contribution will address our strategy for the first bottom-up synthesis of Ge1 xSnx nanowires in a microwave supported, solvent-based growth process without the use of a substrate. The microwave assisted procedure allows us to grow Ge1−xSnx nanowires with tin contents of >11 % (up to 28 %), which is well above the limits of other bottom up approaches in liquids described in literature (<4.3 %).[1] The growth mechanism as well as the active metalorganic species involved in the growth will be discussed.[2] Different growth stages during the formation of nanowires can be distinguished and a diameter dependence of the Sn content in Ge1−xSnx nanowires is observed.