X-ray photoelectron spectroscopic study of silicon surface passivation in alcoholic iodine and bromine solutions

We report an X-ray photoelectron spectroscopic (XPS) study of silicon surfaces passivation using alcoholic solutions of iodine and bromine where different behavior with two systems is observed. The minority carrier lifetime determined by microwave photoconductive decay method showed better surface passivation for iodine-alcoholic system with HF preconditioning step. The iodine-ethanol (I-E) passivated samples show strong Si-I bonding (two times) in Si core level spectra for the samples without oxide (25.5%) compared with oxide (10.2%) counterpart. However, bromine-ethanol (B-E) passivated samples show higher Si-Br bonding strength in the samples with oxide (24.7%) compared to without oxide specimens (12.0%). This may be the reason of difference in passivation behavior of I-E and B-E systems. Higher O-Br bonding in O core level spectra of B-E passivated samples with oxide (35.8%), compared to without oxide (20.7%), results in comparable lifetime values in both with and without preconditioning. To understand the effect of solvent on the passivation, experiments are performed using iodine-methanol (I-M) and bromine-methanol (B-M) solutions and XPS analysis shows similar Si-I, Si-Br, and O-Br bonding trends