Two-Dimensional Ferroelectric In2Se3: Optical Effects on Polarization States and Heterostructure Devices

Jacob Parker

doi:10.7273/000006309

As the downscaling of silicon-based technologies has progressed, fundamental constraints on these convectional materials have made it challenging to keep up with Moore’s law, and eventually, new materials will have to be utilized to progress the downscaling of technologies further ushering in the post-Moore era. Two-dimensional van der Waals (vdW) materials serve to be possible candidates to achieve this as they demonstrate exceptional electrical and optical properties at the monolayer limit, and due to their unique bonding structure can be easily incorporated with disparate materials, allowing for integration into novel heterostructures. Coupling this with the recent discovery of ferroelectricity in vdW materials, new ferroelectric phenomenon and ferroelectric based memory can be demonstrated, and potentially implemented in next generation technologies. In my first work, we realized a ferroelectric field effect transistor (FeFET) structure using mechanically exfoliated vdW ferroelectric α-In2Se3, vdW semiconductor MoS2, and atomic layer deposition(ALD) grown dielectric Al2O3. Utilizing the unique intercorrelated in-plane (IP) and out-of-plane (OOP) ferroelectric polarizations in α-In2Se3 we demonstrate novel FeFET operation by reversing the OOP polarizations through application of an IP bias to achieve non-volatile gating of the MoS2. The fabricated FeFETs exhibited figures of merit with on/off ratios >105 and robust retention times of >102, and showed diminished performed when in an ambient environment, highlighting the importance of an inert environment or surface passivation. In my second work, we investigated optical illumination effects on the ferroelectric polarizations in α-In2Se3 and probe the underlying mechanism for these effects. We demonstrated that optical illuminations can cause uniform ferroelectric domains to become disordered ferroelectric domains, and correlated the disordered states to the illuminations power density and exposure time through piezo-response force microscopy (PFM) and kelvin probe force microscopy (KPFM). Furthermore, it was also shown that these optically induced changes in the ferroelectric domain structure were meta-stable persisting on the order of approximately 102 days. We also verified the optically induced changes could be erased through application of an electric field through an AFM tip or through a gate bias in a device structure, demonstrating reconfigurability of the illuminated region.

Two-Dimensional Ferroelectric In2Se3: Optical Effects on Polarization States and Heterostructure Devices

Files and links (1)

Abstract

Metrics

Details