ABSTRACT
Abstract-Superhydrophobic zinc oxide nanotowers have been grown successfully on silicon surfaces by chemical bath deposition (CBD). Chemically and ultrasonically cleaned silicon substrates were immersed in a beaker containing 100 ml of aqueous 0.1 M Zn(NO3)2 and 4 ml of 28% aqueous NH4OH solution. The CBD was performed in an oven at 70◦C for 20 minutes. The dried samples were passivated using stearic acid (SA) for lowering the surface energy. The SA-passivated samples were annealed at various temperatures ranging from 70◦C to 350◦C. Water contact angle measurements and Fourier transform infrared (FTIR) spectroscopy investigation were performed on the samples at each annealing temperature. The contact angle of water at various temperatures remains nearly constant, at 160◦, with a hysteresis of less than 5◦ and the tendency for the water drop to roll off easily from the surface. FTIR studies reveal that the amount of SA starts to decrease above 200◦C and is completely lost at 350◦C, leaving the sample highly hydrophilic. The partial passivation of the surface due to annealing and the consequent behavior of water contact angle is discussed.
