Journal article Open Access

Hf0.5Zr0.5O2-Based Germanium Ferroelectric pFETs for Nonvolatile Memory Applications

Zacharaki Christina; Chaitoglou Stefanos; Siannas Nikitas; Tsipas Polychronis; Dimoulas Athanasios

Ferroelectric Field-Effect Transistors (FeFETs) with TiN/Hf0.5Zr0.5O2 (HZO) gate stack on germanium p-type channel are fabricated as low voltage non-volatile memory (NVM) devices. The clean HZO/Ge interfaces and the absence of a typical passivation oxide layer resulted in stable and robust ferroelectricity without severe wake-up effect. The impact of unpassivated interfacial defect states on germanium surface on the functionality of transistors is examined. The ferroelectric field-effect is clearly observed and remains during electric field cycling at least until 5∙104 cycles. With the optimum measurement conditions the memory window is MW=0.55 V. Retention measurements up to 104 sec show a small reduction to 0.5 V and from data projection it is inferred that the devices are not expected to fail before 10 years. These first results of HZO-based Ge-FeFETs are promising for the realization of gate-first process and reduced total thermal budget. The lower dopant activation annealing of Ge at ~600oC in comparison with Si at temperatures >1000oC is compatible with the crystallization annealing of HZO, thus the two annealing processes occur simultaneously in one step.

Files (2.6 MB)
Name Size
1.9 MB Download
740.1 kB Download
Views 22
Downloads 15
Data volume 28.3 MB
Unique views 22
Unique downloads 13


Cite as