Figure 3. XPS wide-scan spectrum of untreated Si in (a), Si decontaminated with 5% sodium peroxodisulfate solution and acetone in (b), Si decontaminated with 5% sodium peroxodisulfate solution and acetone, then dipped in a 10% hydrofluoric acid solution to remove the oxidation layer, followed by rinsing with ultrapure water in (c), contamination-free bare Si treated with -MPTS in (d), and contamination-free bare Si treated with TTDCS in (e).