Wet-Chemical Preparation of Silicon Tunnel Oxides for Transparent Passivated Contacts in Crystalline Silicon Solar Cells.

Transparent passivated contacts (TPCs) using a wide band gap microcrystalline silicon carbide (µc-SiC:H(n)), silicon tunnel oxide (SiO2) stack are an alternative to amorphous silicon-based contacts for the front side of silicon heterojunction solar cells. In a systematic study of the µc-SiC:H(n)/SiO2/c-Si contact, we investigated selected wet-chemical oxidation methods for the formation of ultrathin SiO2, in order to passivate the silicon surface while ensuring a low contact resistivity. By tuning the SiO2 properties, implied open-circuit voltages of 714 mV and contact resistivities of 32 mΩ cm2 were achieved using µc-SiC:H(n)/SiO2/c-Si as transparent passivated contacts.