Extrinsic p-type doping of few layered WS_2 films with niobium by pulsed laser deposition

摘要

Doping of few layered 2H WS2 films with Nb by pulsed laser deposition (PLD) using ablation targets fabricated from WS2, S and Nb powders is reported. The undoped controls were n-type, exhibited a Hall mobility of 0.4 cm(2) /Vs, and characterized by a Fermi level at 1.41 eV from the valence band edge. The latter was determined using ultraviolet photoelectron spectroscopy. Films doped at 0.5 and 1.1 atomic percentages niobium were p-type, and characterized by Fermi levels at 0.31 eV and 0.18 eV from the valence band edge. X-ray photoelectron spectroscopy indicates that Nb substitutes on W lattice sites. With increased Nb doping, the hole sheet concentration increased from 3.9 x 10(12) to 8.6 x 10(13) cm(-2), while the mobility decreased from 7.2 to 2.6 cm(2) /Vs, presumably due to increased ionized impurity scattering. The approach demonstrates the potential of PLD for controlled doping of transition metal dichalcogenides. Published by AIP Publishing.