Silicon surface cleaning using XeF2 gas treatment

XeF2 gas treatment has been studied with the aim of finding a new method of silicon surface cleaning. The clean silicon surface is usually obtained by growing a thin oxidized layer on the substrate surface. Then this layer is evaporated by in-situ annealing in ultra-high vacuum (UHV) conditions. In this work, instead of forming a thin oxidized layer, we produced SiFx (x = 1, 2, 3) terminations on the silicon surface treating the surface with XeF2 gas. The treatment in XeF2 vapors cleaned the Si surface from hydro-carbon contaminations so that silicon carbide is not formed on the surface during annealing. The SiFx terminations were completely removed by annealing the Si sample at a temperature higher than 723 K in UHV conditions. After annealing we did not observe any polluting atoms on the surface. Although the clean silicon surface was obtained at a temperature of about 723 K, a high structural perfection of the surface was observed only after additional annealing at 1023 K. This method of silicon surface cleaning, using treatment in XeF2 gas, may be used in molecular beam epitaxy.