Tensilely Strained Ge Films on Si Substrates Created by Physical Vapor Deposition

Ge, owing to its pseudo-direct band gap property and compatibility with Si-based semiconductor technology, is a promising material for Si-compatible photonic devices. Ge-on-Si materials are typically grown in ultra-high vacuum chemical vapor deposition (UHVCVD) systems using toxic and/or flammable Ge precursor gases, such as GeH₄. We demonstrate the creation of Ge films on Si substrates through physical vapor deposition of toxin-free solid Ge sources, where ultra-high purity Ar gas serves as the carrier gas. Structural characterization indicates that a high tensile strain is introduced in the Ge film during the deposition process. A strong peak, resulting from the direct band gap photoluminescence (PL) of Ge, is evident. The growth mechanism, revealed through the evolution of film topography from the early stage of the deposition until a complete film is formed, is currently under investigation and will be reported.