Transport properties of fullerene‐like WS 2 nanoparticles

Electrical resistivity and Hall effect measurements of pellets compacted from fullerene‐like WS 2 nanoparticles ( IF ‐WS 2 ) and bulk 2H‐WS 2 powder were carried out using the van der Pauw method over a wide temperature range. In addition IF ‐WS 2 pellets were annealed at elevated temperatures under vacuum in a specially designed system. Arrhenius plots for the conductivities of the WS 2 samples (2H, IF and IF +annealing) exhibit marked uprise of ∂ ln ( sT –1 )/∂ T –1 with temperature. The resistivity of the non‐annealed IF ‐WS 2 pellets is higher by 2–8 orders of magnitude than that of 2H‐WS 2 pellets, whereas the resistivity of the annealed IF pellets is higher than that of the non‐annealed ones. Hall Effect measurements at 300 K show p‐type conductivity and similar carrier concentration for both types of materials. The carrier mobility of 2H‐WS 2 platelets is found to be in the range of the reported values. However, IF ‐WS 2 pellets have shown an unusually low mobility for a semiconducting material. The experimental data was found to be in a good agreement with a model used for analyzing the conductivity of polycrystalline semiconductors, which takes into consideration fluctuations of the barrier heights among the different nanoparticles as well as within a single nanoparticle boundary. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)