Optics | Physical Sciences and Mathematics | Physics
We discuss unreported transitions of oxidised GaAs surfaces between (super)hydrophilic and hydrophobic states when stored in ambient conditions. Contact angles higher than 90° and high adhesive force were observed for several air-aged epitaxial samples grown under different conditions, as well as on epi-ready wafers. Regardless of the morphologies of the surface, superhydrophilicity of oxygen-plasma treated samples was observed, an effect disappearing with storage time. Reproducible hydrophobicity was likewise observed, as expected, after standard HCl surface etching. The relation between surface oxides and hydrophobic/hydrophilic behaviour is discussed.
A. Gocalinska, K. Gradkowski, V. Dimastrodonato, L. O. Mereni, G. Juska, G. Huyet, and E. Pelucchi , "Wettability and “petal effect” of GaAs native oxides", Journal of Applied Physics 110, 034319 (2011) https://doi.org/10.1063/1.3619797