Narrow Results

Hollow germanium tubular nanostructures have been obtained by a hydrothermal process at a temperature of 400°C and pressure of 7 MPa with quick cooling to room temperature. Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) show that the germanium tubular nanostructures are polycrystalline and have open-end structures at the tips. The diameter of germanium tubular nanostructures is about 40–70 nm and the inner pore size is about 10 nm in average. We propose the rolling mechanism for the formation of tubular nanostructures from lamellar nanostructures to explain the possible formation process of germanium tubular nanostructures.

The ballistic performance of Si and Ge nanowire (NW) is compared in this study. Current–voltage characteristic is obtained by self-consistently solving the nonequilibrium Green’s function (NEGF) transport equation with Poisson’s equation. The result is obtained at $⟨001⟩$ channel orientation. Simulation result shows Ge NW gives higher ON-state current than Si NW, when OFF-state current is made equal by gate metal work function engineering. However, at subthreshold region, performance of NW FET for both material is almost identical. The intravalley and intervalley electron–phonon scattering effect is also calculated using the deformation potential theory and the self-consistent Born approximation. It is found that electron–phonon scattering effect is more pronounced at ON-state of Si NW FET. The ballistic current decreases with the decrease in diameter of the Si NW FET due to electron–phonon scattering.