Cubic Phase Sn-Rich GeSn Nanocrystals in a Ge Matrix

Abstract

We report on the synthesis of a novel optoelectronic material, Sn-rich Ge1–x Sn x nanocrystals in a Ge matrix. The nanocrystals have been formed after annealing of a metastable Ge-rich Ge1–y Sn y film, which was embedded in the Ge matrix. Electron microscopy investigations have revealed that these nanocrystals possess two lattice types: (i) a diamondlike cubic structure with a high Sn fraction (x > 0.5) and (ii) an ordered zincblende structure (x = 0.5).

The thermal stability of epitaxial GeSn layers

“…The weak peak observed at ∼25 • in REL9 is compatible with the presence of few clusters made of ordered Ge 0.5 Sn 0.5 zinc blende structure with a 0.62 nm lattice parameter, most likely located within the epi-layer. 11 Different from the report of Li et al, 6 we do not observe, in samples of comparable Sn content and relaxation degree, Sn clustering in the bulk of the epi-layer. This might be due to the different growth technique (molecular beam epitaxy) and the rather low deposition temperature (160 • C) used in Ref.…”

“…Indeed, Sn surface and volume segregation by formation of Sn-rich nanodots has been evidenced, 11 but the proof of β-Sn formation at large Sn contents, as numerical ab initio calculations suggested, 12 has not been reported yet.…”

(Si)GeSn nanostructures for light emitters

“…The low solubility of Sn in Ge can be used for QDs formation by simply annealing the GeSn layers, which causes the precipitation of Sn 24 . Following this approach to form GeSn QDs we grew Ge/GeSn/Ge single quantum wells (SQW), as depicted in Figure 4 (a), before performing rapid thermal annealing at temperatures between 400°C and 500°C to create Ge1-xSnx precipitations in the bulk material ( Table 1).…”

SnxGe1–x Alloy Nanocrystals: A First Step toward Solution-Processed Group IV Photovoltaics

“…Nonetheless, the synthetic methodology developed in this effort is inspired by that used for pure Ge NCs. 27 Considering the above complications, we have investigated the use of a varied binary combinations of GeI 2 , GeCl 2 , Ge(HMDS) 2 , GeI 4 and Sn(HMDS) 2 , SnCl 2 , (Bu) 2 SnCl 2 , (Bu) 4 Sn and SnI 2 for tin. To synthesize Sn x Ge 1-x NCs in any appreciable amount, we found it necessary to either combine a highly reactive Ge precursor and relatively inert Sn precursor, or a pair of precursors that in-situ form a complex which eventually can be reduced and/or thermolyzed to Sn x Ge 1-x alloy NCs at elevated temperature in the presence of a reducing agent.…”