Ion Implantation as a Method to Form the Porous Germanium with Copper Nanoparticles

Abstract

This is a pioneering work on the low-energy Cu+ ion implantation of a с-Ge single crystal at an energy of E = 40 keV using radiation doses of 1.8 × 1015 to 1.5 × 1017 ion/cm2 and the current density in the ion beam of 5 μA/cm2. The surface morphology of samples after implantation has been inspected via scanning electron microscopy and atomic force microscopy. The composition and structure of samples are studied via the microprobe element microanalysis and electron back-scattering diffraction. It is shown that irradiation doses below 1.8 × 1015 ion/cm2 upon the onset of implantation of lead to the amorphization of the с-Ge surface layer. An increase in the threshold implantation dose above 3.1 × 1015 ion/cm2 causes the formation of Cu nanoparticles in the irradiated Ge layer, which are uniformly distributed across the surface. A sample receiving an implantation dose of 6.2 × 1016 ion/cm2 exhibits the formation of a porous mesh Ge structure with Cu nanoparticles at the nodes. The specific resistance measured for samples depends on the implantation dose, increasing for the amorphous implanted Ge layer and doubly decreasing upon the formation of a porous mesh with Cu nanoparticles.