High-Performance p-Type Quasi-Ohmic of WSe2 Transistors Using Vanadium-Doped WSe2 as Intermediate Layer Contact.

Two-dimensional (2D) transition-metal dichalcogenides (TMDCs), such as tungsten diselenide (WSe2), hold immense potential for applications in electronic and optoelectronic devices. However, a significant Schottky barrier height (SBH) at the metal-semiconductor (MS) interface reduces the electronic device performance. Here, we present a unique 2D/2D contact method for minimizing contact resistance and reducing the SBH. This approach utilizes vanadium-doped WSe2 (V-WSe2) as the drain and source contacts. The fabricated transistor exhibited a stable operation with p-type quasi-ohmic contact and a high on/off current ratio surpassing 108 at room temperature, reaching 1011 at 10 K. The device achieved an on-current of 68.87 µA, a high mobility of 103.80 cm2 V-1 s-1, a low contact resistance of 0.92 kΩ, and remarkably low SBH values of 1.51 meV for holes at VGS = -120 V with fixed VDS = 1 V. Furthermore, a Schottky photodiode has been fabricated, utilizing V-WSe2 and Cr as the asymmetric contact platform, showing a responsivity of 116 mA W1-. The findings of this study suggest a simple and efficient method for improving the performance of TMDC-based transistors.

Ultrafast Negative Capacitance Transition for 2D Ferroelectric MoS2/Graphene Transistor.

Negative capacitance gives rise to subthreshold swing (SS) below the fundamental limit by efficient modulation of surface potential in transistors. While negative-capacitance transition is reported in polycrystalline Pb(Zr0.2Ti0.8)O3 (PZT) and HfZrO2 (HZO) thin-films in few microseconds timescale, low SS is not persistent over a wide range of drain current when used instead of conventional dielectrics. In this work, the clear nano-second negative transition states in 2D single-crystal CuInP2S6 (CIPS) flakes have been demonstrated by an alternative fast-transient measurement technique. Further, integrating this ultrafast NC transition with the localized density of states of Dirac contacts and controlled charge transfer in the CIPS/channel (MoS2/graphene) a state-of-the-art device architecture, negative capacitance Dirac source drain field effect transistor (FET) is introduced. This yields an ultralow SS of 4.8 mV dec-1 with an average sub-10 SS across five decades with on-off ratio exceeding 107, by simultaneous improvement of transport and body factors in monolayer MoS2-based FET, outperforming all previous reports. This approach could pave the way to achieve ultralow-SS FETs for future high-speed and low-power electronics.

Tuning of multi-magnetic phase and exchange bias effect by antisite disorder in Ca-doped La2CoMnO6double perovskites.

The exchange bias effect at the magnetic interfaces and multi-magnetic phases strongly depends on the antisite disorder (ASD) driven spin configuration in the double perovskite systems. The percentage of ASD in double perovskites is extensively accepted as a key for designing diverse new nanospintronics with tailored functionalities. In this regards, we have investigated such ASD driven phenomena in Ca2+doped bulk and polycrystalline La2-xCaxCoMnO6(0 ⩽x⩽ 1) series of samples. The structural and Raman studies provide evidence of an increase in the disorder due to the increment of Ca concentration in the parent compound (x= 0). The enhancement of disorder in the doped system induces various magnetic orderings, magnetic frustration and cluster glass-like behavior, which have been confirmed from AC and DC magnetic studies and neutron diffraction studies. As a result, significantly large exchange bias effects, namely zero-field cooled (spontaneous) and field-cooled (conventional) exchange bias, are found. These results reveal the tuning of ASD by doping, which plays an active role in the spin configuration at the magnetic interfaces.