Light Induced Surface Corrosion of Gallium Arsenide for Immobilization of Oligonucleotide Probes

The potential to modify gallium arsenide (GaAs) surfaces with organic molecules provides possibilities to develop biosensors. Thiol‐terminated oligonucleotides have been self assembled on GaAs substrates. The homogeneity and surface morphology of oligonucleotide films were investigated using atomic force microscopy (AFM) and fluorescence microscopy. X‐ray photoelectron spectroscopy (XPS), and time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) were used to determine the surface elemental composition. When in contact with water, the surface of GaAs tended to reorganize. Elemental mapping indicated that the surface was passivated by thiol linked DNA probes. Extended contact with water increased the extent of oxidation and the quantity of immobilized oligonucleotide probes.