Abstract
We investigate how field-effect doping affects the structural properties, the electronic structure, and the Hall coefficient of few-layers transition-metal dichalcogenides by using density-functional theory. We consider monolayers, bilayers, and trilayers of the H polytype of , , , , and and provide a full database of electronic structures and Hall coefficients for hole and electron doping. We find that, for both electron and hole doping, the electronic structure depends on the number of layers and cannot be described by a rigid band shift. Furthermore, it is important to relax the structure under the asymmetric electric field. Interestingly, while the width of the conducting channel depends on the doping, the number of occupied bands at each given point is almost uncorrelated with the thickness of the doping-charge distribution. Finally, we calculate within the constant-relaxation-time approximation the electrical conductivity and the inverse Hall coefficient. We demonstrate that in some cases the charge determined by Hall-effect measurements can deviate from the real charge by up to 50%. For hole-doped the Hall charge has even the wrong polarity at low temperature. We provide the mapping between the doping charge and the Hall coefficient. We present more than 250 band structures for all doping levels of the transition-metal dichalcogenides considered within this work.
11 More- Received 27 January 2015
- Revised 9 April 2015
DOI:https://doi.org/10.1103/PhysRevB.91.155436
©2015 American Physical Society