Formation of high-Sn content polycrystalline GeSn films by pulsed laser annealing on co-sputtered amorphous GeSn on Ge substrate
Zhang Lu, Hong Hai-Yang, Wang Yi-Sen, Li Cheng †, Lin Guang-Yang, Chen Song-Yan, Huang Wei, Wang Jian-Yuan
       

(color online) Raman scattering spectroscopy of samples: (a) as-deposited a-Ge and poly-Ge crystallized by PLA with 250 mJ/cm2 and RTA at 600 °C, (b) a-Ge0.85Sn0.15 and (c) a-Ge0.8Sn0.2 after the PLA process at energy density of 250 mJ/cm2, 400 mJ/cm2, and 550 mJ/cm2. The insets show trends of FWHM and Δω respected to (a) different crystalline qualities and (b), (c) different energy density. (d) The Ge–Ge mode peak shift Δωstrain+disorder in a-Ge and poly-Ge1−xSnx (0 ≤ x ≤ 0.18) caused by strain and disorder depends on FWHM. The dash line is a linear fit to the data. The inset zooms into the data of poly-Ge1−xSnx (0 ≤ x ≤ 0.18). (e) The Ge–Ge mode peak shift Δωstrain+disorder in poly-GeSn films fabricated from a-Ge0.85Sn0.15 and a-Ge0.8Sn0.2 after PLA with energy density of 250 mJ/cm2, 400 mJ/cm2, and 550 mJ/cm2.