The substrates were dipped in 4 M NaOH solutions for 15 min to remove the acidic contamination. After that the substrates were washed with distilled water and then kept in acetone for 10 min.
The substrates were dipped in4 M NaOH solutions for 15 min to remove the acidic contamination.After that the substrates were washed with distilled waterand then kept in acetone for 10 min.