On the hydrophobicity of modified Ga-polar GaN surfaces

Abstract

In this communication, we show that chemical modifications of etched GaN (with different morphological features) through treatment with trichlorododecylsilane or sputtering nano-Au films followed by covalent binding of 1-dodecanethiol strongly affect surface water repellency characteristics. Binding of 1-dodecanethiol to Au-coated whiskers results in GaN crystals becoming superhydrophobic with the contact angles approaching 150°. For a single type of surface morphology, a pairwise comparison of contact angle values of trichlorododecylsilane- and Au/1-dodecanethiol-modified surfaces provides an insight into relative abundance of –OH groups on GaN's Ga-polar side, which mediate and control binding of the hydrophobic silane compound, but not of thiols.