Fabrication of SiGe/Ge nanostructures by three-dimensional Ge condensation of sputtered SiGe on SiO2/Si substrate

Abstract

In this work, three-dimensional (3D) Ge condensation of sputtered “Si/SiGe” nanostructures on SiO2/Si substrate was investigated. Through varying the width of sputtered Si/SiGe structures from 50 μm to 400 nm, the Ge content of fabricated SiGe structures can be modulated from 0.49 to 1.0 after 3D Ge condensation. By further constructing a width modified nanowire (NW) with adjacent widths of 800 nm and 400 nm before 3D Ge condensation, a Si0.33Ge0.67/Ge heterostructure NW was fabricated after 3D Ge condensation. Due to inter-diffusion of Si and Ge atoms, a ∼2-μm-long region with gradually varied Ge content from ∼0.67 to 1.0 is formed between Si0.33Ge0.67 and Ge. The low Schottky barrier height (0.29 eV) of Ge NW/metal contact and good conductivity of the Ge NW suggest that the 3D Ge condensation technique is very promising for fabrication of scalable and low-cost SiGe or Ge nano-electronic/photonic devices.