There is a growing interest to understand the formation of self-organized nanostructures such as dots and ripples on semiconductor substrates using energetic ion beams which have potential applications in nanophotonics and thin film/nanoscale magnetism as templates. Hence, roles of experimental parameters, viz. ion flux/current density, ion fluence, and angle of incidence of ions become crucial to optimize the nanostructures.

In this paper, we report on evolution of ripple morphology on p-Si(100) surface due to 60 keV Ar⁺-ion implantation at fluences in the range of 1-3×10¹⁸ ions cm^-2 and for incident angles  between 45°-75°. Room temperature implantations were carried out by using a uniform current density of 20 µA cm^-2. Systematic study on ripple formation on Si(100) has been studied for the first time by using such a lower current density and a larger angular window. Atomic force microscopic (AFM) studies indicate that with increasing incident angle ripple wavelength decreases, while its amplitude increases. We also observe a systematic variation in the surface roughness with incident angle and fluence. Micro-Raman studies show that ripple morphology is followed by systematic reduction in crystallinity of Si substrate towards lower incident angles.