Germanium nanostructures by helium plasma irradiation

Abstract

The effects of helium plasma irradiation, which has been widely studied on metals, on germanium have been experimentally investigated. The irradiation temperature ranges from 430 to 720~K, and the incident ion energy ranges from 30 to 100~eV.
From the scanning electron microscope (SEM) observation, it was found that various morphology changes including pits, nanocones, nanopillars and roughened surface occur. The spatial scale of the morphology change was analyzed applying Fast Fourier Transform (FFT) to SEM micrographs. Thermal desorption spectroscopy (TDS) analysis suggested that He atoms implanted on Ge play major roles to form roughened surface at the surface temperature higher than 500~K.