Highly Crystalline Nickel Silicon Sheets on Silicon Substrates Using Hydrogen Plasma Treatment

Abstract

Herein, the evolution of nickel silicide and silicon nanosheets on silicon substrates using CH 4 plasma followed by hydrogen plasma treatment is reported. A 2-5 nm nickel layer is deposited on (100) silicon substrates using e-beam evaporation at 150 C. Hydrogen plasma treatment is the most critical step for the oriented diffusion of nickel atoms through [111] planes of silicon. Moreover, the incorporation of trace values of carbon on silicon is found to be crucial to achieve the oriented diffusion of nickel and formation of nanosheets. The presence of carbon is important to induce strain on [111] planes of silicon and expedite the nickel diffusion between such planes. Although for (100) silicon wafers, an in-depth diffusion of nickel is observed, for (111) substrates, a planar sheet is formed. Unique nanochannels with a depth of 500 nm and width of 50-100 nm are realized on (100) silicon wafers and their length is extended to 100 μm. A thorough examination of the sheets using a transmission electron microscope reveals the presence of quantum dots of nickel, placed within silicon nanostructures. These films are investigated using scanning and transmission electron microscopy, X-ray diffraction, atomic force microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy.