Modification of the Surface of Germanium and the Formation of a Porous Layer During Implantation with Indium Ions

The surface modification of a polished single-crystal c-Ge substrate irradiated with 115In+ ions at an energy of E = 30 keV, a current density of J = 5 μA/cm2, and a wide range of high doses D = 1.8 × 1015–7.2 × 1016 ion/cm2 is studied. The sample morphology is analyzed by high-resolution scanning electron microscopy. It is shown that when the value D = 1.9 × 1016 ion/cm2 is exceeded, the formation of a spongy porous structure (PGe) consisting of intertwining nanowires is observed. The geometric parameters of nanowires change with increasing D. Measurement of the optical reflection spectra R of the In:PGe layers demonstrated that the formed In:PGe material is characterized by a low value of the R coefficient in the spectral region of 220–1050 nm. Thus, such layer could serve as an effective antireflective coating.