Preferred orientation of DNA oligonucleotide probes on the (2×4) reconstructed surface of (001) GaAs

Determination of the orientation of the thiol-derivatized DNA oligonucleotide monolayer on arsenic terminated GaAs(001) has been performed using grazing incidence x-ray scattering. DNA oligonucleotides were observed to orient along the trenches of the 2X direction of the GaAs(001)-(2×4) reconstructed surface, at an angle of 33° with respect to the surface. The addition of mercaptohexanol spacer tended to partially align the DNA oligonucleotides at almost 48° with respect to GaAs (001) surface.