Journal of Physics D, Applied Physics vol:46 issue:15 pages:155501-155508
Silicon foils are fabricated using a low-temperature (<150 degC) lift-off process. The electrical activity of traps present in these foils is analysed by means of deep-level transient spectroscopy, carried out in parallel with electron spin resonance (ESR) studies to assess the atomic nature of traps. Two hole traps are detected in the as-cleaved samples, one of which is associated with a D-line defect. After vacuum annealing, these traps and the D-line disappear but at the same time, a new hole trap is detected associated with the ESR-revealed P b0 recombination centre. After chemical removal of a thin Si layer from the crack surface, the ESR signal disappears. This shows that samples fabricated with this method are largely dislocation-free and no electronic levels in the bandgap remain if a layer of a few mu m is removed from the crack surface.