Low Surface Recombination Velocity on (100) Silicon by Electrochemically Grown Silicon Dioxide Annealed at Low Temperature

This letter investigates silicon dioxide (SiO₂) layers that are electrochemically grown in nitric acid (HNO₃) at room temperature. It examines the dependence of surface recombination velocity (SRV), oxide charge, interface states, and oxide thickness on the concentration of HNO₃. The results show that an SRV of less than 40 cm/s can be attained after SiO₂ is annealed at 400°C in oxygen first and then forming gas. This SRV is similar to that attained by the best thermal oxides. Photoconductance and capacitance-voltage measurements indicate that the low SRV is caused by a large positive charge rather than a low interface state density. The SRV is found to degrade due to a decrease in charge and an increase in interface states, where the rate depends on the HNO₃ concentration in which the SiO₂ layer was grown.