A facile method to fabricate ultrathin vertical ZnO nanowall arrays

We demonstrate a facile method to synthesize ultrathin vertical ZnO nanowall arrays only through a one-step catalyst fabrication procedure. After being coated with uniformly dispersed gold particles, the substrates were polished gently to create discrete gold nanoparticle alignment as catalyst. The commercial ZnO powder and activated carbon powder with an atom ratio of 1:1 were utilized as source materials, and the whole growth process occurred in a conventional tube furnace chemical vapor deposition (CVD) system. The SEM images confirm that the ZnO nanowall arrays grow vertically along certain tracks made by polishing. The walls are about 17 nm wide, 90 nm high and 1 microm long after 90 min growth. After second growth, the nanowalls become 20 nm wide, 205 nm high, and 2 microm long. AFM images indicate that the alignment of discrete Au particles with certain separations due to polishing plays the key role in realizing vertical ZnO nanowall arrays.