The band structure change of Hf0.5Zr0.5O2/Ge system upon post deposition annealing

Hafnium zirconium oxide films have been utilized in negative capacitance (NC) field-effect transistors (FETs). The band alignment of semiconductor and HfZrOx film is critical to obtain high device performance. The band alignment of Hf0.5Zr0.5O2/SiOx/Ge system before and after post deposition annealing at 500 degrees C is studied via angle resolved X-ray photoelectron spectroscopy, synchrotron radiation photoemission spectroscopy and UV-Visible spectroscopy. The band gap of Hf0.5Zr0.5O2 is seen narrowed 0.27 +/- 0.05 eV, and the valence band offset between Hf0.5Zr0.5O2 and Ge decreases 0.25 eV +/- 0.05 eV after PDA at 500 degrees C. Therefore, the conduction band offset is nearly unchanged. This work gives insights into the interface physics about Hf0.5Zr0.5O2/SiOx and is valuable for Ge-based NC pFETs.