Novel Metal-Germinade Schottky Barrier Contacts for Si-Photonics Application

Abstract

To reap the full benefits of superior transport and optical properties of germanium, a low-resistance metal-germanides contact that is compatible with existing Si CMOS process technology would be highly desirable. In this abstract, we report the developments of nickel-germanide (NiGe) contact technology and its combination with Schottky barrier engineering techniques (e. g., dopants and valence-mending absorbate segregations) for contact resistance improvement. In addition, we explore the application of these techniques in NiGe Schottky barrier metal-Ge-metal (MSM) photodetector for low dark current and high speed photodetection applications, such as through Si:C (Metal direct contact on Ge) or Sincorporation (for NiGe). Sulfur is used as example in the valencenmending absorbate scheme in this work. In both cases, significant suppression of dark current (~103 to 104 ×) was observed, with the enhanced hole Schottky barrier heights to 0.49eV (S-incorporated) or 0.52eV (thin Si:C layer). In both surface-illuminated and waveguided schemes, 12-15GHz speed were obtained with 1V operating bias.