Electron beam lithography of GeTe through polymorphic phase transformation

Abstract Finding new phases can deeply understand the fundamental of materials and broaden their practical applications. Here, we report two undiscovered phases of GeTe including the zinc-blende (c-) phase and the hexagonal (h-) phase with interlayer van der Waals gaps. A polymorphic phase transformation from rhombohedral α-GeTe to c- and h-GeTe near room temperature, then supposedly to cubic β-GeTe at higher temperature, is first realized via electron beam irradiation. Theirunderlying thermodynamics and kinetics are illustrated by the in-situ heating experiments and molecular dynamics simulation. Density-functional theory calculation indicates that c-GeTe exhibits typical metallic behavior and h-GeTe is a narrow-gap semiconductor with a strong spin-orbital coupling effect. An atomic-scale electron beam lithography technique is finally developed and adopted to fabricate GeTe-based quantum devices compromising nanopillars and heterostructures of c- and h-GeTe in α-GeTe matrix.