Rhombohedral-stacked bilayer transition metal dichalcogenides for high-performance atomically thin CMOS devices

Abstract

Van der Waals coupling with different stacking configurations is emerging as a powerful method to tune the optical and electronic properties of atomically thin two-dimensional materials. Here, we investigate 3R-stacked transition-metal dichalcogenides as a possible option for high-performance atomically thin field-effect transistors (FETs). We report that the effective mobility of 3R bilayer WS 2 (WSe 2 ) is 65% (50%) higher than that of 2H WS 2 (WSe 2 ). The 3R bilayer WS 2 n-type FET exhibits a high on-state current of 480 μA/μm at V ds = 1 V and an ultralow on-state resistance of 1 kilohm·μm. Our observations, together with multiscale simulations, reveal that these improvements originate from the strong interlayer coupling in the 3R stacking, which is reflected in a higher conductance compared to the 2H stacking. Our method provides a general and scalable route toward advanced channel materials in future electronic devices for ultimate scaling, especially for complementary metal oxide semiconductor applications.

Resolidified Chalcogen‐Assisted Growth of Bilayer Semiconductors with Controlled Stacking Orders

“…Second, interestingly, we find that the 3R-stacking bilayer WS 2 exhibits better electrical performance than the 2H-stacking bilayer WS 2 , which may be attributed to the both different intrinsic carrier mobility caused by interlayer coupling [18] and distinct contact resistances. We compared the electrical performance of 3Rand 2H-stacking bilayer WS 2 with other works, [20,[32][33][34][35][36][37][38][39] and found that our bilayer WS 2 shows a comparable on/off ratio and good mobility (Figure 4f and Table S2, Supporting Information). It is acknowledged that the electrical performance of 2D nanoplatesbased devices is determined by the intrinsic carrier mobility of the 2D materials and extrinsic parameters such as contact resistance, parasitic capacitance, and leakage current.…”

“…This feature will lead to the non-uniformity in optical and electrical properties. [20,21] Further exploration to obtain bilayer materials with controlled and tunable stacking order is needed.…”

Electronic properties of rhombohedrally stacked bilayer WSe2 obtained by chemical vapor deposition

“…show respective WSe 2 crystals with ML (light color) and bilayer regions (darker color) in 2H and 3R configurations, characterized by 60 • and 0 • rotational alignments of the upper WSe 2 layer with respect to the base WSe 2 MLs respectively [15,21,24]. The corresponding atomic configurations are illustrated in Figs.…”

“…Nevertheless, some differences between the WSe 2 2H and 3R bilayers are revealed by PL measurements: the different peak wavelengths (1565 and 1572 meV) and peak full width at half maximum (FWHM, 62 and 44 meV, for the 3R and 2H stacking respectively). For both stacking the stark decrease in intensity indicates that the PL is dominated by momentum-indirect transitions at room temperature, but temperature-dependent measurements are required to study the details of the possible optical transitions [21,24,27].…”

Interfacial Effect on the Transient Dielectric Function and Charge Transfer in a Monolayer WS2/Si Heterojunction

“…Furthermore, monolayer WS 2 showcases advantageous characteristics, such as substantial optical absorption, a significant exciton binding energy, and high carrier mobility. Therefore, all these unique properties of monolayer WS 2 give birth to a collection of WS 2 -based optoelectronics, such as modulators, detectors, and light sources. − …”