Interaction of Pd with Strained Layers of Si1-xGex Epitaxially Grown on Si(100)

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Abstract
This work describes the interaction of Pd with MBE grown strained epitxial layers of Si1-x Ge x on Si(100), at low and at high temperatures (250°C and 550°C). Pd was deposited to a thickness of 1700 Å, on the Si1-x Ge x /Si(100) layers with thicknesses of 3300 Å and 2300 Å, and with a Ge contents of x=0.09 and 0.18, respectively. Samples were annealed at temperatures ranging from 250 to 550°C. The reaction products were investigated by Transmission Electron Microscopy, Energy Dispersive Spectroscopy, X-ray dlffraction and Auger Electron Spectroscopy. Strain in the Si1-x Ge x layers was measured by Double Crystal X-ray Diffractometry. Diodes were prepared on n-type substrates, and were characterized by current-voltage techniques. The low temperature interaction is characterized by uniform incorporation of Si and Ge in the Pd2Si1-y Ge y compound (textured on the Si1-x Ge x substrate), and at high temperatures a Ge rich double layer strcucture formed, accompanied by strain relaxation of the Si1-x Ge x layer. The measured Schottky barrier heights were φb=0.67 and 0.65 for x=0.09 and x=0.18, respectively.