LBIC characterization of LPE Si layers deposited on multicrystalline Si sub strates

Silicon layers are deposited by liquid phase epitaxy (LPE) and the transfer of defects and impurities from the substrate to the layer during the deposition is investigated when multicrystalline Si substrates are used. Silicon layers are grown from indium solution in a slider boat apparatus; the maximum layer thickness is 20 μm. The layers and the substrate are characterized by means of the light beam induced current mapping technique (LBIC) at different wavelengths, which led to a map of the recombining defects and to the evaluation of their recombination strength. Collecting structures are p-n junctions obtained by phosphorus diffusion at 850 °C for 30 min. The fit of the computed spectral variation of the internal quantum efficiency with experimental measurements allows the evaluation of the minority carrier diffusion length in the layer and in the substrate. It is found that the extended crystallographic defects of the substrate are transferred in the layer. However, their recombination strength is less marked in the layer, probably due to a recorded impurity concentration and as a consequence, the effective diffusion length is higher in the grains of the layer than in the substrate.