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 GeO
_x
interfacial layer (IL) of HfO
₂
-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 GeO
_x
volatilization. A Ti-doped GeO
_x
gate stack exhibited a lower interface state density of approximately 6×10
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/cm
²
at V
_FB
-1V. Additionally, the Ge pMOSFET with Ti-doped GeO
_x
reveals an improved subthreshold swing of 92 mV/decade and an effective hole mobility of 98 cm
²
/ V\centerdot s. Therefore, the proposed scheme is simple for use in achieving a sub-nm EOT gate dielectric on a Ge substrate.