Laser‐induced heating of porous Ge layers implanted with Ag+ and Cu+ ions

Abstract

AbstractPorous Ge layers consisting of nanowires were formed by low‐energy high‐dose implantation of monocrystalline c‐Ge substrate with Ag+ and Cu+ ions. The obtained layers were studied by Raman spectroscopy using solid‐state and He‐Ne exciting lasers with wavelength of 532 and 633 nm, respectively. The crystalline volume fraction and local temperature of porous layers at the surface sites of laser probing were determined. To interpret the change in the shape of the spectra under the action of laser radiation, deconvolution into amorphous and nanocrystalline components was carried out. Analysis of the spectral line shape made it possible to estimate the crystalline and amorphous volume fractions. The quantum confinement model for Ge nanocrystallites was taken into account for accurate estimations of volume fractions. These estimates showed that the implanted amorphous layers of all samples were locally crystallized with a solid‐state laser. He‐Ne laser excitation resulted in partial crystallization only for layers obtained by Cu+ ion implantation. The measured ratio of the Stokes to anti‐Stokes components demonstrated that the porous layers obtained by implanting Ag+ ion were not heated by a He‐Ne laser and according to the analysis of spectral lines, the crystalline volume fraction did not appear in these layers during probing. The results obtained are explained by the difference in the penetration depth for various samples of the exciting radiation.