Ripple wavelength dependence on ion bombardment energy

Abstract

Under certain conditions, ion bombardment of semiconductors can lead to the formation of a ripple structure on the surfaces of these materials. This paper considers the dependence of the ripple wavelength on the ion energy. It considers and develops ion energy dependence of the Bradley-Harper theory in two limiting conditions. The one limit considers high temperature and low ion areic dose rate conditions, while the other limit applies to low temperatures and high areic dose rates. The paper gives a review of the experimental data available for Si, GaAs and InP and compares the data to the Bradley-Harper predictions. There is limited quantitative agreement with the low temperature and high areic dose rate predictions. The (limited) discrepancies are probably due to the other factors determining the ripple wavelength. The various experimental studies, employed in these comparisons, used different angles of incidence of the bombarding ions, different ion areic doses and different areic doses rates. All these ion parameters might influence the degree of surface diffusion and, therefore, also the wavelength of the bombardment-induced ripples.