Investigation on Germanium Transistors with HfOx-Based Gate Stacks for CMOS Operations

Tzu Chieh Hong, Chun Jung Su*, Yao Jen Lee, Yiming Li, Seiji Samukawa, Tien Sheng Chao

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Germanium (Ge) FinFETs with HfOx-based gate stacks are fabricated to study the CMOS applications. To evaluate the logic circuit operation, the associated CMOS inverters are characterized. Compared to the HfO2, the Hf0.5Zr0.5Ox (HZO) gate stack provides higher drive currents and more symmetric Vth behaviors, which should be associated with the polarization effect. Through cyclic voltage transfer characteristic (VTC) operation and systematical analysis, it is found that both polarization and charge trapping in the gate stack impact the device characteristics. The HZO devices show a negative VTC shift with cycling, while the HfO2 devices reveal a positive shift. This opposite VTC behavior for both gate stack schemes indicates that the interaction of interface states and dipoles significantly influences the device operation. The results revealed in this work present a comprehensive understanding of HfOx-based device optimization.

Original languageEnglish
Article number015005
JournalECS Journal of Solid State Science and Technology
Issue number1
StatePublished - Jan 2024


  • electron devices
  • films


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