Optical and recombination properties of dislocations in cast-mono silicon from short wave infrared luminescence imaging

Abstract

We demonstrate the use of the D1/D2 defect luminescence spectral range (1400 nm < λ < 1700 nm) of dislocations in cast-mono silicon to access geometrical tilt and opto-electronic recombination properties in their vicinity. The angle between dislocation and surface was determined thanks to the spatial asymmetry of the PL intensity in the regions close to the dislocations. Our optical model relies on the classical recombination–diffusion continuity equation as well as simple optical absorption and light propagation properties. It takes advantage of the optical transparency of silicon for wavelengths above 1400 nm. Carrier transport properties such as nonradiative lifetime around that location are also investigated. The model is discussed with a parameter study and the unicity of the extracted parameter set has been confirmed. As an example, we find out an angle of a selected dislocation pattern of about 25.4° with respect to the surface and an effective lifetime of 0.8–0.9 μs.