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.