Unveiling the electronic properties of GeAs, a novel anisotropic 2D semiconductor

The resurgence of interest in the study of black phosphorus has demonstrated the importance of band-gap tunability and the need to extend the study of two-dimensional (2D) layered materials to include anisotropic crystals. Aim of this proposal is to explore the electronic properties of GeAs, exponent of a new family of 2D layered semiconductors. Based on our preliminary results conducted on high-quality single crystals, the band dispersion is highly anisotropic. This agrees with the anisotropic mobility observed in electronic transport measurements. In the proposed experiment, we first intend to perform a detailed photon energy scan to fully access the band dispersion over the entire Brillouin zone. Second, we plan to study how alkali atoms adsorbed on the pristine surface of GeAs can be used to manipulate the band-gap, in analogy with similar studies on black phosphorus and other 2D materials. If positively evaluated, our experiment will map for the first time the anisotropic electronic properties of a new family of 2D layered semiconductors, which may find future applications in polarization-sensitive photodetectors and devices for optical communication.