Highly-ordered ripple structure induced by normal incidence sputtering on monocrystalline GaAs (001): ion energy and flux dependence

• GaAs (001) surfaces are sputtered by low energy Ar+ ions at elevated temperature.
• Ripple formation driven by Ehrlich–Schwoebel instability is observed.
• The evolution of ripples with ion energy and current density is presented.

Low energy ion beam sputtering induced nanostructure formation on GaAs (001) surfaces at elevated temperature and at normal ion incidence has been studied for different ion energy and flux of the incident Ar+. Well-ordered nanoripples are found to develop, whose wave-vector is oriented along 〈110〉〈110〉 crystallographic direction. The ripple structure is found to coarsen with ion energy, while it remains invariant with the ion flux. The evolution of the ripples can be attributed to the biased diffusion of vacancies arising from Ehrlich–Schwoebel barrier.