Improving thermal stability for ge p-mosfet of HfO₂-based gate stack with ti-doped into interfacial layer by in-situ plasma-enhanced atomic layer deposition

We successfully fabricated a Ge pMOSFET with Ti that is doped into a GeOx interfacial layer (IL) of HfO2 -based gate stacks, doing so using in situ plasma-enhanced atomic layer deposition. X-ray photoelectron spectroscopy (XPS) spectra findings indicated that Ti-doped IL can suppress GeOx volatilization. A Ti-doped GeOx gate stack exhibited a lower interface state density of approximately 6\times 10 {{11}} eV-1 cm-2, an equivalent oxide thickness (EOT) of 0.7 nm, and a relatively low gate leakage current of approximately 10-4 A/cm2 at \text{V} {{FB}} -1\text{V}. Additionally, the Ge pMOSFET with Ti-doped GeOx reveals an improved subthreshold swing of 92 mV/decade and an effective hole mobility of 98 cm2 / \text{V}\centerdot \text{s}. Therefore, the proposed scheme is simple for use in achieving a sub-nm EOT gate dielectric on a Ge substrate.