Evolution of surface morphology of ion sputtered GaAs(1 0 0)

Abstract

In order to explore possible route to fabricate nano-scale semiconductor dots, a series of ion bombardment experiment on GaAs(1 0 0) was undertaken using a high current isotope separator and ion implanter with ⁴⁰Ar⁺ ions of an energy of 60 keV incident at an angle of 60° with respect to surface normal. Detailed surface topographical features of the bombarded samples were characterised by atomic force microscopy. To observe the growth of topography with time, the samples were bombarded at a number of doses. At a dose of 1×10¹⁷ ions/cm², no observable topography was developed. At a dose of 2×10¹⁷ ions/cm², the topography started to develop in the form of roughness along with islands or dots formation on the crest of waves or hillocks. Similar kind of topography has been observed up to a dose of 1×10¹⁸ ions/cm², remarkable with the formation of nano-dots with the maximum dimension of a few hundred nanometer. At the dose of 3×10¹⁸ ions/cm² the surface became populated with ripple morphology without formation of any island or dot, in contrast with lower doses.