Epitaxial growth of WTe2 on graphene, a candidate for low-power electronics.
Summary :
One of today’s societal challenges is to reduce the power consumption of electronic components. A recently developed approach involves ferroelectric control of charge or spin transport. In this context, WTe2 appears to be a high-potential candidate, as its ferroelectricity has been confirmed down to two monolayers, and its electronic band structure is characterized by spin polarization induced by strong spin-orbit coupling. Mastering the epitaxial elaboration to obtain homogeneous films at cm2 scale and nanometric thicknesses required for application remains a complex task, due to the differences in thermodynamic properties between metal and Te atoms.
In this work, carried out in collaboration with several French laboratories, we have gone beyond the state of the art in terms of the lateral size of the growth islands at the origin of the films (>100nm) and in terms of the thickness of the films (>5nm). We propose a simple analytical model for understanding and potentially predicting growth conditions. The electronic properties of ultrathin films have been confirmed by synchrotron-based angle-resolved photoemission spectroscopy measurements in agreement with ab initio electronic band structure calculations.
