부산대학교 도서관

In this article, the effect of the various processing steps during the fabrication of c-Si/SiO x /SiC x fired passivating contacts on the silicon bulk lifetime is studied, and the kinetics of defect deactivation by hydrogenation is investigated. It is found that the firing step at 800 °C induces shallow bulk defects in float-zone silicon wafers, which can subsequently be passivated with hydrogen provided by an a-SiN x :H/D reservoir layer upon annealing at 450 °C. Experimental results and numerical data treatment indicate a rapid passivation of the surface within less than 1 min, followed by a slower passivation of the shallow bulk defects. In situ lifetime measurements are consistent with a slow bulk lifetime improvement by showing similar lifetime evolutions for both p-type and n-type SiC x layers. The kinetics of the hydrogenation process seems to be limited by the available hydrogen supply at the c-Si/SiO x interface, rather than by its diffusion within the bulk of the wafer. Moreover, it is affected by the bulk doping as well as the SiC x layer thickness. Finally, it is shown that hydrogenation is also possible with an a-SiN x :H/D reservoir layer deposited on one side of the wafer only, although resulting in a lower passivation level (${{\boldsymbol{\tau }}_{\mathbf{eff}}}$ ∼700 μ s compared to ${{\boldsymbol{\tau }}_{\mathbf{eff}}}$ ∼1300 μ s for symmetrical samples), and slower kinetics (${{\boldsymbol{\tau }}_{\mathbf{reac}}}$ ∼5 min comparedto ${{\boldsymbol{\tau }}_{\mathbf{reac}}}$ ∼0.8 min).