研究目的
To assess the formation of ripple patterns in bulk ZnO by ion beam sputtering (IBS) at medium energy (20 keV) using Ar+ ions and to analyze the ripple patterns regarding the roughness, ripple wavelength, and order. Additionally, to evaluate the ion beam modification of the material using spectroscopic ellipsometry (SE) to model both the optical damage and the roughening of the surface, and to extract the main optical parameters after the irradiation.
研究成果
The study demonstrated the formation of ripple nanopatterns on bulk ZnO crystals by means of irradiation with 20 keV Ar+ ions. The ripple dynamics follows a power law dependence for both the roughness and the wavelength. A 3-layer SE optical model was used to model the damage and the roughness evolution of the samples. The optical constants of the damaged ZnO layer exhibit a reduction of the refractive index with fluence and an enhanced absorption below the bandgap. The irradiated samples were not completely amorphized, even at large fluences, confirming the radiation resistance of the material.
研究不足
The study is limited by the high level of damage and roughness at high fluences, which makes the deconvolution of both effects very difficult. Additionally, the implantation effect of the Ar ions might also play a role in the damaged layer, leading to the inclusion of voids.
