Transition Metal Dichalcogenides (TMD) (MX2, M=Metal, X=S,Se,Te) have been attracted great interest due to their rich properties [1, 2] and the possibility of growing them in thin films layer by layer with a promising potential in nanoelectronics [3, 4]. The MX2 compounds can crystalize into various phases with different properties (2H,1T,1T’ or Td). For instance, the well-known MoS2 crystalizes in the hexagonal 2H prismatic crystal which is a semiconductor with a sizeable gap . The 2H phase is also the most stable for MoTe2, but in this case, it could be also prepared in the orthorhombic Td phase which has been proved a Type II Weyl semimetal (WSM) , a new form of topological quantum matter. Besides WSM, the 3D Dirac semimetal (DSM) is also a class of topologically non-trivial matter. The DSMs, known also as ‘3D graphene’, are formed by conduction and valance band crossing at some point of the Brillouin zone with a linear dispersion in all three directions in k-space. Most experimentally proven DSM (Na3Bi, Cd3As2) [7,8] are bulk materials. On the other hand, ditellurides can be crystalized in stable atomically thin film.
Here we present results on high quality HfTe2 thin films grown by MBE on AlN(0001)/Si(111) substrates. The quality of the structure was investigated by means of RHEED, STM and high resolution TEM. The electronic band structure of the HfTe2 was imaged along high symmetry crystallographic directions in the surface Brillouin zone by using in situ ARPES and compared with DFT calculations that suggests the presence of non-trivial topology.
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