Room temperature ferroelectric thin films are the key element of high density, low consumption nonvolatile memories. However, with the further miniaturization of the electronics devices beyond the Moore’s law, conventional ferroelectrics suffer great challenge arising from the critical thickness effect, where the ferroelectricity is unstable if the film thickness is reduced to nanometer or single atomic layer limit. Two-dimensional (2D) materials, thanks to their stable layered structure, saturate interfacial chemistry, weak interlayer couplings, and the benefit of preparing stable ultra-thin film at 2D limit, are promising for exploring 2D ferroelectricity and related device applications. So far, proof of concept demonstrating 2D ferroelectricity has predominantly utilized small flakes (less than a few hundred µm) mechanically exfoliated from a bulk crystal. In particular, atomically thin alpha (or gamma)-In2Se3 lamellar semiconductor preserves a ferroelectric character at 2D limit.
Given the imperative for wafer-scale electronics applications, there is a pressing need for large area growth of high quality 2D materials using bottom-up processes. The objective of this PhD project is to develop the growth of lamellar In2Se3 in its alpha or gamma phase crystal structures by chemical vapor phase epitaxy (MOCVD) on large silicon substrates (200 mm). The proof of concept of a ferroelectric memory cell will be performed by directly depositing a metal electrode on the surface of the 2D ferroelectric material without damaging it.