Diffusion of iron into solar-grade CIGS layers from natural and radioactive front-side sources

Diffusion of Fe in CIGS was investigated on solar-grade CIGS layers using radiotracer sputter-profiling of 59Fe or in-depth secondary ion mass spectrometry (SIMS) of natural iron isotopes. In both cases natural or radioactively labelled iron was deposited on the front-surface of CIGS/Mo/float-glass samples. Fe penetration profiles were measured after isothermal annealing in a lamp oven at different temperatures. A diffusivity of 4 × 10− 13 cm2 s− 1 was deduced from Gaussian-type SIMS profiles originating from annealing at 300 °C. It was found that pronounced sputter-broadening effects may complicate the interpretation of the diffusion profiles.