Depth profile analysis of solar cell silicon by GD-MS

Abstract

In this work we have assessed the capability of depth profile analysis by glow discharge mass spectrometry (GD-MS) for several impurities relevant for solar cell silicon. Fast-flow direct-current high resolution GD-MS has been used. Six multicrystalline p-type silicon samples with contamination of B, P, Ti, Fe and Cu have been investigated. Ion implantation has been used for impurity contamination with a target depth of 3 μm. The acquisition time was approximately 30 seconds, giving a depth resolution of approximately 0.5 μm. The GD-MS concentration profiles of the samples contaminated with B, P and Ti agreed well with the levels implanted. Because Fe and Cu are fast diffusers, their distribution deviates from the target implantation. This indicates that for fast diffusing transition metallic impurities, such as Fe and Cu, different impurity distribution mechanisms occur and should be taken into account when analysing their depth profiles.