Design of a remote plasma-enhanced chemical vapor deposition system for growth of tin containing group-IV alloys

Group-IV alloys of Ge and/or Si with Sn are challenging to prepare due to the low solubility of Sn in both of these elements. Herein, we describe a remote plasma-enhanced chemical vapor deposition (RPECVD) system designed to synthesize such group-IV alloys. Thin films of Ge, Ge1−ySiy, Ge1−xSnx, and Ge1−x−ySiySnx were deposited in the range of 280−410 °C on Si (001) substrates utilizing a remote He plasma with downstream injected mixtures of SnCl4, SiH4, and/or GeH4 precursors. The composition and structural properties of these RPECVD films were characterized with x-ray diffraction, transmission electron microscopy, and x-ray photoelectron spectroscopy. They were found to be crystalline, oriented with the substrate, and nearly relaxed due to the formation of an ∼5 nm thick interface layer with a high density of edge dislocations and stacking faults.