Investigation of strain-induced phase transformation in ferroelectric transistor using metal-nitride gate electrode

In this work, we report a ferroelectric memory with strained-gate engineering. The memory window of the high strain case was improved by ∼71% at the same ferroelectric thickness. The orthorhombic phase transition (from ferroelectric to anti-ferroelectric transition) plays a key role in realizing negative capacitance effect at high gate electric field. Based on a reliable first principles calculation, we clarify that the gate strain accelerates the phase transformation from metastable monoclinic to orthorhombic and thus largely enhances the ferroelectric polarization without increasing dielectric thickness. This ferroelectric strain technology shows the potential for emerging device application. (Figure presented.).