Hall and field-effect mobilities in few layered p-WSe2 field-effect transistors

• DOI: 10.1038/srep08979
• Publication Date: 2015-03-11T10:43:54Z
• Authors: N. R. Pradhan; D. Rhodes; S. Memaran; J. M. Poumirol; D. Smirnov; S. Talapatra; S. Feng; N. Perea-Lopez; A. L. Elias; M. Terrones; P. M. Ajayan; L. Balicas
• Keywords: Condensed Matter - Mesoscale and Nanoscale Physics; Mesoscale and Nanoscale Physics (cond-mat.mes-hall); 0103 physical sciences; FOS: Physical sciences; 01 natural sciences; 7. Clean energy; Article

AbstractHere, we present a temperature (T) dependent comparison between field-effect and Hall mobilities in field-effect transistors based on few-layered WSe2 exfoliated onto SiO2. Without dielectric engineering and beyond a T-dependent threshold gate-voltage, we observe maximum hole mobilities approaching 350 cm2/Vs at T = 300 K. The hole Hall mobility reaches a maximum value of 650 cm2/Vs as T is lowered below ~150 K, indicating that insofar WSe2-based field-effect transistors (FETs) display the largest Hall mobilities among the transition metal dichalcogenides. The gate capacitance, as extracted from the Hall-effect, reveals the presence of spurious charges in the channel, while the two-terminal sheet resistivity displays two-dimensional variable-range hopping behavior, indicating carrier localization induced by disorder at the interface between WSe2 and SiO2. We argue that improvements in the fabrication protocols as, for example, the use of a substrate free of dangling bonds are likely to produce WSe2-based FETs displaying higher room temperature mobilities, i.e. approaching those of p-doped Si, which would make it a suitable candidate for high performance opto-electronics.