Thickness-Dependent Interfacial Coulomb Scattering in Atomically Thin Field-Effect Transistors

Abstract

Two-dimensional semiconductors are structurally ideal channel materials for the ultimate atomic electronics after silicon era. A long-standing puzzle is the low carrier mobility (μ) in them as compared with corresponding bulk structures, which constitutes the main hurdle for realizing high-performance devices. To address this issue, we perform a combined experimental and theoretical study on atomically thin MoS2 field effect transistors with varying the number of MoS2 layers (NLs). Experimentally, an intimate μ-NL relation is observed with a 10-fold degradation in μ for extremely thinned monolayer channels. To accurately describe the carrier scattering process and shed light on the origin of the thinning-induced mobility degradation, a generalized Coulomb scattering model is developed with strictly considering device configurative conditions, that is, asymmetric dielectric environments and lopsided carrier distribution. We reveal that the carrier scattering from interfacial Coulomb impurities (e.g., chemical residues, gaseous adsorbates, and surface dangling bonds) is greatly intensified in extremely thinned channels, resulting from shortened interaction distance between impurities and carriers. Such a pronounced factor may surpass lattice phonons and serve as dominant scatterers. This understanding offers new insight into the thickness induced scattering intensity, highlights the critical role of surface quality in electrical transport, and would lead to rational performance improvement strategies for future atomic electronics.

Giant magneto-optical Raman effect in a layered transition metal compound

“…S6). Note that the values of the optical mobility determined in the present work are much larger than those measured using transport measurements (21)(22)(23)(24)(25) but similar to the values obtained in a high-k HfO 2 gated field-emission transistor (20,26). Furthermore, our results are also greater than the calculated phonon-scattering-limited value of ∼400 cm 2 /V·s (27).…”

Analysis of optical and electronic properties of MoS2 for optoelectronics and FET applications

“…In general, this unique property of MoS 2 , and 2D materials enables the creation of atomically smooth material sheets and the precise control on its number of molecular layers. The indirect to direct crossover occurs at the mono-layer limit resulting in strong contrast in photoluminescence efficiency between mono-and multi-layer sheets [15][16] [27][28][29][30]. The atomically-thin mono-or multi-layer MoS 2 allows excellent gate electrostatics to suppress short channel effects (SCE), which is one of the major issues in scaled MOSFETs.…”

Hybrid quantum dot-tin disulfide field-effect transistors with improved photocurrent and spectral responsivity

“…For example, l in monolayer MoS 2 reported in early studies was lower than 10 cm 2 V À1 s À1 , 26 but it was later shown that the use of graphene contact and h-BN encapsulation could enhance the measured l in monolayer MoS 2 above 1000 cm 2 V À1 s À1 , 27 and even as high as 34 000 cm 2 V À1 s À1 for six-layer MoS 2.…”