A DLTS and RBS analysis of the angular dependence of defects introduced in Si during ion beam channelling using 435 keV alpha-particles

It is generally assumed that ion beams (IBs) used during channelling experiments create little damage when incident along a direction of low crystallographic index of a crystal lattice. We have employed deep level transient spectroscopy (DLTS) to characterise the defects produced by 435 keV alpha-particles in a Si lattice incident along the 〈1 0 0〉 axis (α = 0°) as well as at small angles (α ≤ 7°) with respect to this direction. The commonly observed high energy (MeV) alpha-particle-induced point defects (V-O and V-Sb pairs and the two charge states of the divacancy, V₂) could be observed for angles of incidence as small as 0.35°. The concentration of the primary defects was observed to decrease for α ≥ 2.45°. Furthermore, isochronal annealing experiments showed that a DLTS defect peak which is superimposed on the V^=/-₂, and observed predominantly for α ≥ 2.45°, could be a V-related defect. Current-voltage (I-V) and capacitance-voltage (C-V) measurements also showed that Schottky barrier diodes (SBDs) fabricated on the exposed samples became less rectifying with increasing angle of incidence.