Nano patterning and structuring of InP(100) by low energy ion beam irradiation

InP(100) crystal surfaces were irradiated by ion beams with low energy (180–225 eV) and high flux (∼ 1015/cm2 s) and the self-organization process induced by the ion beam was investigated by examining nanostructures formed during the ion beam exposure. An electrostatic closed electron Hall drift thruster with a broad beam size was used as an ion source. While the incident angle (θ), ion flux (J), and ion fluence (ϕ) were changed and the InP crystal was rotated, cone-like, ripple, anisotropic nanostructures were observed on the surface by an atomic force microscope. The wavelength of the ripple was about 40 nm, which is smaller than values ever previously reported, and the dependence of ripple wavelength on ion flux follows well the predictions of the Bradley–Harper model. As the incident angle was varied, the root mean square of the surface roughness slightly increased up to the critical angle and then suddenly decreased, presumably due to the decrease of sputtering yield. Continuous rotation of the sample led to the formation of nano dots with the size of 95–260 nm.