Nanoscale triboactivity of functionalized c-Si surfaces by Fe⁺ ion implantation

In the present work, we present a study of the effect of Fe(+) ion implantation on the tribological response at nanoscale contact lengths of crystalline silicon (c-Si) surfaces. (1 0 0) silicon wafers were implanted with Fe(+) at a fluence of 2  ×  10(17) cm(-2), followed by annealing treatments at temperatures of 800 °C and 1000 °C. After microstructural characterization, nanoabrasive wear tests were performed with an atomic force microscope (AFM) using an AFM diamond tip with a stiff steel cantilever that enables the application of loads between 1 μN and 8 μN. After the nanowear tests, the same AFM was used to visualize and measure the worn craters. It was observed that the as-implanted samples present the poorest nanowear response, i.e. the highest wear rate, even higher than that of the unimplanted Si wafers used as a reference. Nevertheless, annealing treatments result in a measurable increase in the nanowear resistance. In this way we show that Fe(+) ion implantation of c-Si, followed by the proper post-heat treatment, results in the formation of FeSi2 nanoprecipitates finely dispersed in a recrystallized matrix. This can be a valuable way of optimizing the nanotribological behavior of silicon.