Energy Band Alignment Study on ZnO and Hafnium Zirconium Oxide(Hf0.5Zr0.5O2)Stack
Hf0.5Zr0.5O2(HZO)overcomes thedefects of traditional ferroelectric materials.It is compati-ble with CMOS processing and is scalable,which makes it a great development potential in high-end chip field.The bottleneck of HZO is the low cycle life.Most of researchers attempt to improve its ferroelectric properties and extend its lifespan through interface engineering,dielectric miscellaneous and other arts and crafts.ZnO is used as a transition layer between HZO and top electrode and the HZO/ZnO stacks are fab-ricated.The fundamental physical aspects of the ZnO transition layer and its interface with HZO,inclu-ding the energy band structure and the impact of annealing on energy band alignment are studied by using X-ray photoelectron spectroscopy.The results indicate that element diffusion and dipole moments change occur at the interface during the annealing process,resulting in a variation of the energy band offset in HZO/ZnO,and a transition of the heterojunction from type-Ⅱ to type-Ⅰ.This work provides a fundamental physical basis for ZnO transition layer in improving the lifespan of HZO-based memories.
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