Thermal and electron-beam-induced reaction of disilane on Si(100)-(2×1)

We present results of detailed studies of the adsorption and thermal and electron-beam-induced dissociation of disilane of Si(100)-(2×1) using ultraviolet photoemission spectroscopy, thermal desorption spectroscopy, and electron-stimulated desorption. We show that at 90 K the disilane adsorbs mainly molecularly on Si(100)-(2×1), but above ∼200 K it dissociates by breaking the Si-Si bond. The resulting ${\mathrm{SiH}}_3$ surface species decompose above ∼525 K to give ${\mathrm{H}}_2$ and a monohydridelike Si-H surface layer. The dangling bonds of this surface are saturated, and the surface is unreactive. Above 700 K the Si-H surface layer decomposes into ${\mathrm{H}}_2$ and a reactive (2×1)-reconstructed surface is regenerated on which disilane can again dissociate. We show that an electron beam effectively dissociates disilane on the surface, providing a means to grow hydrogenated amorphous silicon films at low temperatures.