About a novel gettering procedure for multicrystalline silicon samples

Aim of this work was to study the effects of heat treatments, in the temperature range 450-850 degrees C, on the electrical properties of multicrystalline silicon samples. The influence of the gas atmosphere was also explored. Diffusion length (L-d) measurements, by the Surface Photovoltage technique (SPV), and electrical conductivity measurements were used to characterize samples before and after the heat treatments. It was shown that treatments at 700 degrees C in air induce a systematic increase of L-d, which is larger in the case of samples with the lowest initial values of L-d. When the same procedure is carried out in different atmospheres either a decrease or a negligible variation of the original values of L-d is observed. We associate the L-d improvements after the annealing in air to a gettering mechanism induced by the presence of a Si/SiO2 interface, created by the surface oxidation of silicon.