Swelling and sputtering of porous germanium by silver ions

Surface processes for porous Ge (PGe) formed by low-energy high-dose implantation of Ag+ with an energy of E = 30 keV and a current density J = 5 μA/cm2 in dependence of the radiation dose D = 6.2·1014–1.5·1017 ion/cm2 where observed. Using X-ray photoelectron spectroscopy, it was found that for selected implantation conditions at D ≥ 9.3·1015 ion/cm2, Ag nanoparticles were synthesized in Ge, but formation of silver germanide (GeAg4) was not occur. Using scanning electron and atomic-force microscopy it was found that with increasing D up to ~1.9 × 1016 ion/cm2 , a layer of porous germanium (Ag:PGe) is formed, accompanied by swelling of the implanted Ge surface up to 25 nm thick. With a further increase of D > 1.9·1016 ion/cm2, the opposite effect is observed, which consists of sputtering PGe at a constant rate of ~3.6 nm/min and an sputtering yield of ~17.2.