No abstract

One-dimensional (1D) van der Waals (vdW) materials offer nearly defect-free strands as channel materials in the field-effect transistor devices and probably, a better interconnect than conventional copper with higher current density and resistance to electro-migration with sustainable down-scaling. We report a theoretically predicted halide based 1D few-chain atomic thread, PdBr2, isolable from its bulk which crystallizes in a monoclinic space group C2/c. Liquid phase exfoliated nanowires with mean length (20 ± 1)μm transferred onto a SiO2/Si wafer with a maximum aspect ratio (length:width) of ≈5000 confirm the lower cleavage energy perpendicular to the chain direction. Moreover, an isolated nanowire can also sustain a current density of 200 MA/cm2, which is atleast one-order higher than typical copper interconnects. However, local transport measurement via the conducting atomic force microscopy (CAFM) tip along the cross direction of the single chain records a much lower current density due to the anisotropic electronic band structure. While 1D nature of the nanoobject can be linked with a non-trivial collective quantum behavior, vdW nature could be beneficial for possible pathways in an interconnect fabrication strategy with better control of placement in an integrated circuit.

Tuning the ambipolar behavior in charge carrier transport via defect-engineering is crucial for achieving high mobility transistors for nonlinear logic circuits. Here, we present the electric-field tunable electron and hole transport in a microchannel device consisting of highly air-stable van der Waals (vdW) noble metal dichalcogenide (NMDC), PdSe2, as an active layer. Pristine bulk PdSe2 constitutes Se surface vacancy defects created during the growth or exfoliation process and offers ambipolar transfer characteristics with a slight electron dominance recorded in field-effect transistor (FET) characteristics showing an ON/OFF ratio <10 and electron mobility ∼21 cm2/(V·s). However, transfer characteristics of PdSe2 can be tuned to a hole-dominated transport while using hydrochloric acid (HCl) as a p-type dopant. On the other hand, the chelating agent EDTA, being a strong electron donor, enhances the electron-dominance in PdSe2 channel. In addition, p-type behavior with a 100 times higher ON/OFF ratio is obtained while cooling the sample down to 10 K. Low-temperature angle-resolved photoemission spectroscopy resembles the p-type band structure of PdSe2 single crystal. Also, first principle density functional theory calculations justify the tunability observed in PdSe2 as a result of defect-engineering. Such a defect-sensitive ambipolar vdW architecture may open up new possibilities toward future CMOS (Complementary Metal-Oxide-Semiconductor) device fabrications and high performance integrated circuits.