Rapid thermal processing effect on the intragrain and grain boundaries properties of multicrystalline silicon solar cells

A high-performance light-beam-induced-current (LBIC) analyzer has been used to determine the influence of rapid thermal annealing (RTA) on the minority-carrier diffusion length (L). For this purpose, a Schottky diode (Al/Si) was fabricated on polycrystalline p-type silicon. The contacts were obtained by a cold technology. The diffusion length was determined by a laser spot scanning method. The results of a detailed analysis of the effect of various RTA parameters, such as plateau temperature and duration, on L as deduced from the LBIC analysis of the corresponding Schottky diodes are reported. Presently reported investigations of the effect of RTA on the intragrain transport properties showed nearly no variation in L for samples subjected to treatments below 500°C. On the other hand, a sharp decrease in L, and consequently a degradation in the overall solar cell efficiency, for samples subjected to RTA during 10 s in the range of 600-900°C are obtained. For longer annealing time (up to ≈30 s), a partial recovery effect is observed