Sven Barth1,Raphael Behrle2,Masiar Sistani2,Jos Haverkort3,Michael Seifner4
Goethe University Frankfurt1,TU Wien2,TU Eindhoven3,Lund University4
Sven Barth1,Raphael Behrle2,Masiar Sistani2,Jos Haverkort3,Michael Seifner4
Goethe University Frankfurt1,TU Wien2,TU Eindhoven3,Lund University4
This contribution will address the formation of nanowires and nanorods of metastable composition and demonstrate the significant changes in physical properties associated with their composition.[1] All the growth studies are carried out either in solution or by gas phase techniques using the metal to be incorporated in the Ge host lattice as a growth seed. This approach allowed the formation of highly crystalline, metastable Ge<sub>1-y</sub>Ga<sub>y</sub> (y~0.03%) as well as Ge<sub>1-x</sub>Sn<sub>x</sub> (x=0.13-0.28) nanowires and nanorods at low temperatures.[2-4] The materials have been characterized by different analytical methods including TEM, EDX, Raman spectroscopy as well as XRD. Generally, a homogeneous incorporation of unusually high contents of Sn and Ga in the Ge lattice has been observed. The high incorporation efficiency also alters the physical properties significantly. While hyperdoped Ge<sub>0.97</sub>Ga<sub>0.03</sub> shows quasi-metallic behavior in temperature dependent transfer characteristics, Ge<sub>0.81</sub>Sn<sub>0.19</sub> reveals still semiconducting behavior in equivalent experiments. Moreover, the formation of Ge<sub>1-x</sub>Sn<sub>x</sub> with x>0.09 causes the transformation to a direct bandgap material, while the solid solubility limit according to the binary phase diagram (~ 1 at% Sn in Ge) has to be overcome. The efficient absorption and emission in the mid-IR range (<~0.55 eV) makes Ge<sub>1-x</sub>Sn<sub>x</sub> very attractive for CMOS-compatible optoelectronics based purely on group IV elements. The high crystal quality of CVD-grown, epitaxial Ge<sub>0.81</sub>Sn<sub>0.19</sub> nanowires can be illustrated.<br/><br/><br/><i>References </i><br/>[1] <i>Chem. Mater.</i> <b>2020</b>, <i>32,</i> 2703-2741<br/>[2] ACS Nano <b>2018,</b> 12, 1236.<br/>[3] Chem. Mater. <b> 2017</b>, <i>29</i>, 9802.<br/>[4<sup>] </sup>ACS Nano <b>2019</b>,<i> 13, </i>8047