Atomistically observing real-space structure of composition modulated (Nb0.94V0.06)10(SixGe1−x)7nanowires with ultralow resistivity

Abstract

We have synthesized quaternary single crystalline (Nb_0.94V_0.06)₁₀(Si_xGe_1−x)₇ nanowires (NWs) (0.1 ≤ x ≤ 0.5) in high density by flowing a NbCl₅ precursor and placing vanadium (V) foil on a mixture of Si, Ge, and C powder. The composition of Si (x) in the NW could be modulated from 0.1 to 0.5 by changing the substrate temperature. We have investigated how the atoms comprising the quaternary NWs are arranged in a real-space using a spherical aberration corrected scanning transmission electron microscope. The filling of Si and Ge atoms in Ge atom columns is analyzed by comparing experiments and simulations. Electrical transport measurements show that (Nb_0.94V_0.06)₁₀(Si_0.5Ge_0.5)₇ NWs have an ultralow resistivity of ∼8.5 μΩ cm, lower than that of most conducting metal silicides, as well as a high failure current density of 1.1 × 10⁸ A cm⁻² at room temperature. The synthesis of quaternary single crystalline (Nb_0.94V_0.06)₁₀(Si_xGe_1−x)₇ NWs (0.1 ≤ x ≤ 0.5) shows that Si and Ge composition can be easily modulated in metal germanosilicide nanostructures. The quaternary NWs may supply high quality nanoscale materials for the gate and interconnect in SiGe based nanoelectronics.