Raman scattering characterization of Si(100) implanted with mega-electron-volt Sb

Abstract

Dose dependent structural modifications in Si(100) due to 1.5 MeV implantation of Sb have been characterized using Raman spectroscopy and Rutherford backscattering spectrometry/channeling (RBS/C) techniques. With increasing fluence, an intensity reduction of the first order Raman peak, characteristic of crystalline Si, is observed. The amorphicity in Si lattice appears at a dose of 1×1013 ions/cm2 and it increases with each dose. For a dose of 5×1014 ions/cm2 the Raman spectrum resembles that of amorphous Si. RBS/C studies also support a fully amorphized lattice at this dose though for smaller doses it suggests lower disorder. For the fluences of 1×1013 and 1×1014 ions/cm2 a coexistence of undamaged crystalline Si regions and amorphous zones is observed. Consequently, phonon confinement is observed. Lattice recovery achieved by subsequent annealing has also been investigated using Raman spectroscopy. By annealing at 600 °C, sample crystallinity is fully recovered in all the cases up to the fluence of 5×1014 ions/cm2. For higher doses small amorphicity still remains. Depth dependent measurements of the shifts in the Raman peaks demonstrate a gradient in stress which is of compressive nature near the surface region but is tensile in deeper layers. Maximum stress in the lattice appears for a dose of 1×1012 ions/cm2 which gets relaxed by the incorporation of amorphous zones at higher fluences.