Cubic Phase Sn-Rich GeSn Nanocrystals in a Ge Matrix

We report on the synthesis of a novel optoelectronic material, Sn-rich Ge_1–xSn_x nanocrystals in a Ge matrix. The nanocrystals have been formed after annealing of a metastable Ge-rich Ge_1–ySn_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).