Low surface recombination velocity in n-Si passivated by catalytic-chemical vapor deposited alumina films

The surface recombination velocity (S0) in n-type Si (n-Si) wafers has been reduced below 0.1 cm/s by dint of positive fixed charges created by alumina (AlOx) films deposited at a film-temperature of 230 °C by catalytic chemical vapor deposition (Cat-CVD) using trimethyl aluminum (TMA) and O2. Positive fixed charges of the order of 1012 charges/cm2 can be created in AlOx films deposited under O2/TMA flow-rate ratios in the range of 3.5-6.5. The extremely small S0 has been confirmed to be obtainable mainly due to a band bending effect brought about by the positive charges. The polarity and amount of the fixed charges can be determined by the flow-rate ratio of O2/TMA.