[100] silicon wafers were selected as substrates for this experiment for ease of cleaving. 1cm 2 silicon squares were manually cleaved face-up on aluminum foil surface via a diamond-tip scribe tool. Silicon substrates were then immersed in ethanol and cleaned first in an ultrasonic bath for 10 minutes and then rinsed in a mixture of deionized water. In addition, the substrates also went through a second cleaning process of immersion in deionized water, 90% hydrogen peroxide, and 96% sulfuric acid (Sigma-Aldrich) at a 1:1:3 volume ratio for 30 minutes. The samples were then rinsed thoroughly three times with deionized water and blow-dried with extra-dry compressed nitrogen before spin coating.