Ferroelectric doped hafnium oxide and its application on electronic devices

Ferroelectricity is the material property such that we can induce spontaneous polarization, reverse it and modulate it by varying the applied electrical field on the ferroelectric material. Recently, doped hafnium oxide (HfO2) has garnered attention with its excellent scalability, reliability, and compatibility with the current CMOS process. This thesis introduces two research projects aimed at improving the electrical properties of ferroelectric-doped HfO2 for various device applications. In the first project, we demonstrate a high-performance ferroelectric aluminum (Al) doped HfO2 capacitor with Ti/Pd gate electrode. The remnant polarization reaches up to 20 µC/cm2, endurance higher than 10^8 cycles and retention over ten years at room temperature. In the second research, we demonstrate a ferroelectric tunneling junction (FTJ) based on metal/aluminum oxide/zirconium doped HfO2/silicon structure. We show that this FTJ has artificial synaptic behavior with symmetric synaptic weight change and tunable conductance. We also show spike-timing-independent plasticity (STDP) can be obtained in this device, which proves the possibility of using our FTJ as a neuromorphic computing chip