Controllable growth of large-size α-GeTe nanosheets with ferroelectricity by substrate pre-annealing†

The atmospheric chemical vapor deposition (APCVD) method has been widely applied to synthesize high-quality two-dimensional materials. GeTe has many intriguing properties, such as phase transition, thermoelectric and ferroelectricity, which allow unique opportunities for functional ferroelectric devices. Here, we systematically investigated effects of various parameters during the growth of α-GeTe nanosheets on mica by APCVD. Single-crystal α-GeTe nanosheets possess a lateral size of up to ∼30 μm and a thickness as low as ∼8.6 nm. It was found that substrate pre-annealing significantly impacted the nucleation density of α-GeTe nanosheets. Furthermore, the room-temperature ferroelectric properties of α-GeTe nanosheets grown by CVD are reported for the first time. This work offers an effective accessible method for the controllable growth of large-size 2D α-GeTe to explore its fascinating multiferroic properties.