Thermally activated p- and n-doped passivation layers

Amorphous phosphorus- and boron-doped silicon carbide films are used below a silicon nitride capping layer to passivate p-type silicon. It is shown that the nitride capping layer in combination with a high temperature step similar to a contact firing step - but with lower peak temperature - can significantly improve the passivation quality of boron-doped silicon carbide. In spite of the silicon nitride capping a slight accumulation at the silicon surface is created, which is detected by surface photovoltage measurements (SPV). A second very simple qualitative test in order to verify the disadvantageous existence of inversion conditions underneath a passivation layer is presented and is based on checking whether the depletion region modulation (DRM) affects the low injection lifetime measured via quasi-steady-state photoconductance.