On the c-Si/SiO_2 interface recombination parameters from photo-conductance decay measurements

摘要

The recombination of electric charge carriers at semiconductor surfaces continues to be a limiting factor in achieving high performance optoelectronic devices, including solar cells, laser diodes, and photodetectors. The theoretical model and a solution algorithm for surface recombination have been previously reported. However, their successful application to experimental data for a wide range of both minority excess carrier concentrations and dielectric fixed charge densities has not previously been shown. Here, a parametrisation for the semiconductor-dielectric interface charge Q_(it) is used in a Shockley-Read-Hall extended formalism to describe recombination at the c-Si/SiO_2 interface, and estimate the physical parameters relating to the interface trap density D_(it), and the electron and hole capture cross-sections σ_n and a_p. This approach gives an excellent description of the experimental data without the need to invoke a surface damage region in the c-Si/SiO_2 system. Band-gap tail states have been observed to limit strongly the effectiveness of field effect passivation. This approach provides a methodology to determine interface recombination parameters in any semiconductor-insulator system using macro scale measuring techniques.