Shallow boron implantations in Ge and the role of the pre-amorphization depth

The impact of the Ge pre-amorphization conditions on shallow B profiles, resulting from a 1 keV implantation in n-type Ge and a 500 °C 1 min rapid thermal anneal, is investigated. In general, an increase of the sheet resistance with lower Ge energy is observed. There is some evidence for tail diffusion, enhancing slightly the junction depth and reducing its steepness. This could point to end-of-range-mediated transient-enhanced diffusion (TED) of B in Ge. It is clear that for this to happen, a pre-amorphization is required which contains completely the B profile.