Fabrication of nanostructures on InP(100) surface with irradiation of low energy and high flux ion beams

Abstract

InP(100) crystal surface was irradiated by ion beams with low energy <TEX>$(180\~225\;eV)$</TEX> and high flux <TEX>$(\~10^{15}/cm^2/s)$</TEX>, Self-organization process induced by ion beam was investigated by examining nano structures formed during ion beam sputtering. As an ion source, an electrostatic closed electron Hall drift thruster with a broad beam size was used. While the incident angle <TEX>$(\theta)$</TEX>, ion flux (J), and ion fluence <TEX>$(\phi)$</TEX> were changed and InP crystal was rotated, cone-like, ripple, and anistropic nanostrucuture formed on the surface were analyzed by an atomic force microscope. The wavelength of the ripple is about 40 nm smaller than ever reported values and depends on the ion flux as <TEX>$\lambda{\propto}J^{-1/2}$</TEX>, which is coincident with the B-H model. As the incident angle is varied, the root mean square of the surface roughness slightly increases up to the critical angle but suddenly decreases due to the decrease of sputtering yield. By the rotation of the sample, the formation of nano dots with the size of <TEX>$95\~260\;nm$</TEX> is clearly observed.