Grant, NicholasMcIntosh, Keith2015-12-10June 19-24http://hdl.handle.net/1885/60386This work investigates the surface passivation achieved by growing silicon dioxide (SiO2) electrochemically in concentrated nitric acid (HNO3) at room temperature, a procedure that has the potential to be significantly less ex pensive than the thermal oxides used in high-efficient solar cells and test structures. The SiO2 layers are formed by two methods: direct-current (DC) electrochemical oxidation and alternating-current (AC) electrochemical oxidation. Prior to annealing, both methods offer poor passivation, however after annealing in oxygen and then forming gas, surface recombination velocities (SRV) of 35 cm/s and 15 cm/s are achieved for the DC and AC methods, respectively. In the case of the DC oxidation, the low SRV is achieved by the presence of a high positive charge density of Qf = 3.1012 cm-2 and a high interface defect density of Dit >1013 cm-2eV-1, whereas the SRV obtained by the AC oxidation results from a lower Qf of <1.1012 cm-2 and Dit of 1011 cm-2eV-1, which is more desirable for solar cell passivation. In quantifying the SRV more precisely, we have used a HF passivation method to monitor the bulk lifetime. In some cases the bulk lifetime has been shown to decrease from ∼ 11 ms to ∼ 500 μs after DC and AC oxidation method followed by a low temperature anneal (400°C). However by cleaning the silicon wafers using the RCA method prior to oxidation, very little contamination is observed.Keywords: Alternating current; Bulk lifetime; Concentrated nitric acid; Direct-current; Forming gas; Interface defects; Low temperatures; Passivation methods; Positive charge density; Room temperature; Surface passivation; Surface recombination velocities; Test str201110.1109/PVSC.2011.61859182016-02-24