Structural and optical properties of porous silicon prepared by anodic etching of irradiated silicon

Porous silicon (pSi) is considered to be a potential material in the field of electronics and optoelectronics because of its strong luminescence in visible and near-infrared region. Swift Heavy Ion (SHI) beam irradiation shows versatile effects on physical and optical properties of porous silicon. The p-type (1 0 0) Si was irradiated with 80 MeV Ni ions at various fluences ranging from 1 × 1011 to 5 × 1013 ions/cm2. The irradiated samples were anodically etched to get porous Si. Field Emission Scanning Electron Microscope (FESEM) images confirm the presence of uniform sponge like surface in pSi layers. The photoluminescence (PL) peak position is found to shift towards the higher wavelength (red shift) by increase in fluence. The increased defect states are expected to be responsible for the observed exponential degradation in PL intensity. The pSi layer thickness is found to decrease with increase in fluence. The refractive index (n) measurements on pSi were consistent with structural and optical measurements. Finally we found that Ni ion irradiation promotes aging effects leading to some observable blue shift in PL.