Bombardment-induced ripple topography on GaAs and InP

Abstract

Bombardment-induced ripples have possible application in nano-technology as nano-wires. This paper reviews some of the published experimental data of ripple formation on GaAs and InP resulting from noble gas, oxygen, nitrogen and cesium ion bombardment. The dependences of the ripples and their corresponding wavelengths on substrate temperature, areic dose and (to a lesser extent) angle of incidence were considered. The experimental results were tested against the predictions of the Bradley–Harper theory [J. Vac. Sci. Technol. A 6 (1988) 2390]. Surprisingly good agreement was obtained between the experimental data and this theory. This is probably due to the amorphisation of the substrates under ion bombardment and, thereby, minimising the effect of crystallographic-orientated self-diffusion on metals, and of energy barriers (Ehrlich–Schwoebel barriers) to interlayer surface diffusion. From the data of MacLaren et al. [J. Vac. Sci. Technol. A 10 (1992) 469], the activation energy for surface self-diffusion of GaAs in the temperature range 60–100 °C was determined as 0.26 eV.