Fig. 4. (a) Electronic behavior of two-terminal Ge0.81Sn0.19 NW devices after annealing at 523 K for 15, 30, and 60 min. Three different cases of specific device behavior including device failure (α) with breaking at the electrode-NW contact as shown in the inset, resistivity decrease followed by an increase (β) and a steady decrease in resistivity (γ) can be observed. The data presented are from individual devices and not averaged. (b) The XRD of NW material annealed for 60 min at 523 K show Ge0.81Sn0.19 NW degradation and segregation of β-Sn (ICDD 04-0673). (c) An EDX line scan shows a highly degraded Ge1–xSnx NW and the corresponding mapping in the inset, which could be associated with α-behavior in (a). A partial segregation is shown in (d) that can be assigned to a β-behavior in (a). The I–V diagrams in (e) illustrate the β- and γ-behavior of devices in another representation as shown in (a).
