3.1 Preparation of substrate for growth

By using the diamond cutter, Si substrates were cut in suitable sizes and shapes. In order to avoid the contamination, the substrates were cleaned before the deposition of catalyst, as oily layer and dust particles may stick to the surface of the substrates. For the cleaning purpose, the acetone was poured into a beaker, and the beaker was filled up to half level. The substrates were put into the acetone-filled beaker to completely immerse in them. The acetone-filled beaker was placed in ultrasonic bath at room temperature for 30 min. Si (100) substrates were then put into ethanol and deionized water for decontamination purpose for 30 min.
