On the c-Si/SiO2 interface recombination parameters from photo-conductance decay measurements

Abstract

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 Qit is used in a Shockley-Read-Hall extended formalism to describe recombination at the c-Si/SiO2 interface, and estimate the physical parameters relating to the interface trap density Dit, and the electron and hole capture cross-sections σn and σp. This approach gives an excellent description of the experimental data without the need to invoke a surface damage region in the c-Si/SiO2 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.

Dielectric surface passivation for silicon solar cells: A review

“…In n‐type silicon, where passivation is more effective, Larionova et al demonstrated a S eff of 0.42 cm s −1 , and Bonilla et al obtained 0.17 cm s −1 , for 2.5 and 1 Ωcm resitivities, respectively. They reported that the mechanisms involved in such good passivation were a combination of the intrinsic field‐effect due to grown‐in charge in the nitride layer, the extrinsic chemical passivation of the Si–SiO 2 interface (due to hydrogen ingress during PECVD deposition of the nitride), and the subsequent addition of extrinsic field‐effect via corona discharge . When used on a textured surface, Bonilla et al reported a S eff of 34 cm s −1 in an as deposited oxide‐nitride stack, and 14 cm s −1 after extrinsic addition of charge.…”

Passivation of Liquid‐Phase Crystallized Silicon With PECVD‐SiNx and PECVD‐SiNx/SiOx

“…A reduction in Q IL,eff could be caused by the injection of charge carriers from the silicon into the IL stack which is possible with the O/N IL stack under applied voltage conditions as discussed above (section 4.2) and which might happen under illumination as well . Furthermore, when the interface defect density is of the same order as the fixed charge density, the charge associated with interface defects could reduce the effectiveness of the field‐effect passivation …”

Scalable Techniques for Producing Field-Effect Passivation in High-Efficiency Silicon Solar Cells

“…This will be explored in detail in Section IV. The resulting interface charge ranges from 1.5 to 2.8 × 10 12 q/cm 2 , which includes values of dielectric charge necessary for highquality FEP as modelled in [40]. The effective lifetimes produced with these quantities of ionic interface charge are all similar, despite an increase in FEP caused by the increasing interface charge.…”