Ion beam analysis of plasma immersion implanted silicon for solar cell fabrication

Abstract

Phosphorus ions were implanted using plasma immersion ion implantation (PII) to create shallow pn junctions in solar cells. Depths of PII phosphorous were shallow enough to be analyzed by Rutherford Backscattering Spectrometry (RBS) combined with the channeling technique. It was shown that PII is able to produce a high enough surface concentration of phosphorous (several times 10 21 cm −3) for shallow pn junctions. RBS revealed that after 5 minutes of implantation phosphorus surface concentrations remained almost unchanged due to the balance of implantation and surface sputtering. A heavily damaged layer was found at the surface, the thickness of which was comparable to the range of the co-implanted hydrogen depth profile. Electrical activation of the implanted phosphorus and junction depth measured by Spreading Resistance Profiling (SRP) were favourable for short time PII of about 1–5 minutes.