Y.S. Li, J. Ngyuen
California State University,
Keywords: Ge, Si-compatible photonic devices, tensile strain, physical vapor deposition, toxin-free, environmentally friendly
Summary:Tensilely strained Ge is a promising material for Si-compatible photonic devices. The current technology to make Ge-on-Si materials involves Ge film deposition in a high-cost ultra-high vacuum chemical vapor deposition (UHVCVD) system 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 in a low-cost CVD system, where Ar gas serves as the carrier gas. Structural characterization indicates that our samples are of high crystalline quality, and a tensile strain of 2% or higher is introduced in the Ge films during the deposition process. A direct band gap photoluminescence (PL) peak is evident in the PL spectra of these tensilely strained Ge films. This low-cost environmentally friendly approach of creating Ge-on-Si materials might present new opportunities for overcoming the material challenges for silicon-compatible photonic devices.