Recombination via nano-precipitates … a new mechanism for efficiency loss in solar silicon?

Fast diffusing metals in silicon can form large precipitates. Although such precipitates can be damaging because of junction leakage they are not powerful recombination centers. In contrast we have investigated the precipitation of slow diffusing metals and found that they can produce nano-precipitates with dimensions of 2 to 10 nm. These have strong recombination activity. In this paper we focus on molybdenum nano-precipitates and present an analysis of recombination behavior derived from deep level transient spectroscopy. The chemical species of the nano-precipitates has been determined using transmission electron microscopy.