Controlled vapor phase growth of germanium selenide and germanium microflakes

Abstract

Graphene and transition metal dichalcogenides have been intensively investigated in recent years. Germanium selenide (GeSe) has emerged lately as a new low-symmetry two-dimensional material due to its extraordinary in-plane anisotropic electrical, optical, and optoelectronic properties. However, the controlled synthesis of large-scale GeSe flakes is still a significant challenge because of its strong interlayer coupling and low lattice symmetry. In this work, we have achieved the synthesis of rectangular GeSe microflakes (MFs) with lateral sizes up to 0.33 mm on the glass substrate via a vapor phase deposition technique. The lateral size, thickness, and growth mode of GeSe MFs can be effectively tuned based on space-confined and substrate engineering strategies. Germanium (Ge) MFs with triangular and hexagonal morphologies were simultaneously fabricated in the high-temperature zone. Our experimental results demonstrated that the growth temperature plays an important role in the selective growth of GeSe and Ge MFs. A corresponding growth mechanism has been discussed in detail based on systematic characterizations. Our work provides a new route for the controlled growth of large-size GeSe and Ge MFs, which promotes a promising future in the fields of novel optoelectronic devices.