Ultrafast 27 GHz cutoff frequency in vertical WSe2 Schottky diodes with extremely low contact resistance

Abstract

Ultra-thin two-dimensional semiconducting crystals in their monolayer and few-layer forms show promising aspects in nanoelectronic applications. However, the ultra-thin nature of two-dimensional crystals inevitably results in high contact resistance from limited channel/ contact volume as well as device-to-device variability, which seriously limit reliable applications using two-dimensional semiconductors. Here, we incorporate rather thick twodimensional layered semiconducting crystals for reliable vertical diodes showing excellent Ohmic and Schottky contacts. Using the vertical transport of WSe 2 , we demonstrate devices which are functional at various frequency ranges from megahertz AM demodulation of audio signals, to gigahertz rectification for fifth-generation wireless electronics, to ultraviolet-visible photodetection. The WSe 2 exhibits an excellent Ohmic contact to bottom platinum electrode with record-low contact resistance (~50 Ω) and an exemplary Schottky junction to top transparent conducting oxide electrode. Our semitransparent vertical WSe 2 Schottky diodes could be a key component of future high frequency electronics in the era of fifth-generation wireless communication.

Visualizing Spatial Evolution of Electron-Correlated Interface in Two-Dimensional Heterostructures

“…The interfacial electronic structure has a significant influence on the properties of solid materials, − which must be in contact with other materials to realize practical applications. For the electron-correlated material systems expected for future electronic devices, the interfacial electronic state can always induce fascinating properties, such as high-temperature superconductivity − and unusual magnetism. , Mott insulator, − a representative member of electron-correlated materials, has been predicted to own intermediate electronic structures and properties at the interface contacted with other materials, , such as metallic state penetration and Kondo proximity. , However, despite the developing theoretical prediction, the experimental visualization of interfacial electronic structures is still rare, due to the difficulties in three-dimensional systems that the interface always exists in the inner.…”

Rapid and up-scalable manufacturing of gigahertz nanogap diodes

“…The large difference observed between the intrinsic and the extrinsic f C values are most likely attributed to parasitic losses associated with the rectifier circuit employed 5 , and highlight the possibility for further improvements. Despite the nonidealities, the extrinsic f C of our diodes surpass those achieved previously using different processing technologies and/or semiconductor materials, such as solution-processable metal oxides 5 , 7 , 9 , 19 – 22 , organic polymers 23 – 26 , organic small-molecules 27 – 30 , and various low-dimensional semiconductors 4 , 31 . Figure 5 summarizes the most important developments over the years in the area of emerging Schottky diodes technologies with the details of each study listed in Supplementary Table 4 .…”

Ultrafast flash memory with large self-rectifying ratio based on atomically thin MoS2-channel transistor

“…The more negative the V FG applied, the larger the reverse reaction ratio obtained. The maximum reverse rectification ratio reaches ∼10 8 at V DS = ±2 V and V FG = −0.5 V. This value is larger than most reported for 2D material-based Schottky diodes [30,31], backward diodes [32][33][34], and van der Waals p-n heterojunction diodes [35,36]. Figure 2(f) shows the transfer characteristics of the transistor at V DS = 0.5 V. When V FG is swept between −1 V and 1 V, I D increases with increasing V FG , proving the n-type behaviour of the MoS 2 channel.…”