화학공학소재연구정보센터
Applied Surface Science, Vol.323, 40-44, 2014
Effective surface passivation of p-type crystalline silicon with silicon oxides formed by light-induced anodisation
Electronic surface passivation of p-type crystalline silicon by anodic silicon dioxide (SiO2) was investigated. The anodic SiO2 was grown by light-induced anodisation (LIA) in diluted sulphuric acid at room temperature, a process that is significantly less-expensive than thermal oxidation which is widely-used in silicon solar cell fabrication. After annealing in oxygen and then forming gas at 400 degrees C for 30 min, the effective minority carrier lifetime of 3-5 Omega cm, boron-doped Czochralski silicon wafers with a phosphorus-doped 80 Omega/square emitter and a LIA anodic SiO2 formed on the p-type surface was increased by two orders of magnitude to 150 mu s. Capacitance-voltage measurements demonstrated a very low positive charge density of 3.4 x 10(11) cm(-2) and a moderate density of interface states of 6 x 10(11) eV(-1) cm(-2). This corresponded to a silicon surface recombination velocity of 62 cm s(-1), which is comparable with values reported for other anodic SiO2 films, which required higher temperatures and longer growth times, and significantly lower than oxides grown by chemical vapour deposition techniques. Additionally, a very low leakage current density of 3.5 x 10(-10) and 1.6 x 10(-9) A cm(-2) at 1 and -1 V, respectively, was measured for LIA SiO2 suggesting its potential application as insulation layer in IBC solar cells and a barrier for potential induced degradation. (C) 2014 Elsevier B.V. All rights reserved.