a pathway for defect-free electrical contact to 2D semiconductors and open up possibilities for circuits with efficient switching characteristics and higher efficiency optoelectronic devices.Van der Waals (vdW) heterostructures, [21] especially when passivated with hexagonal boron nitride (h-BN), [22,23] present an excellent platform for studying the Schottky-Mott limit. Graphene, [24,25] a semimetal with a gate-tunable work function, [26] is a promising alternative to traditional bulk metal electrical contacts to 2D semiconductors. [16] In lieu of using different metals, we propose a modified Schottky-Mott rule for gate-tunable Schottky junctions in which the gate voltage (V G ) directly modulates the barrier height (Φ B ), When 1901392 (2 of 5) www.advmat.de www.advancedsciencenews.com
Conflict of InterestThe authors declare no conflict of interest.
In the development of semiconductor devices, the bipolar junction transistor (BJT) features prominently as being the first solid state transistor that helped to usher in the digital revolution. For any new semiconductor, therefore, the fabrication and characterization of the BJT are important for both technological importance and historical significance. Here, we demonstrate a BJT device in exfoliated TMD semiconductor WSe2. We use buried gates to electrostatically create doped regions with back-to-back p-n junctions. We demonstrate two central characteristics of a bipolar device: current gain when operated as a BJT and a photocurrent gain when operated as a phototransistor. We demonstrate a current gain of 1000 and photocurrent gain of 40 and describe features that enhance these properties due to the doping technique that we employ.
The three pillars of semiconductor device technologies are (1) the p-n diode, (2) the metal-oxide-semiconductor field-effect transistor and (3) the bipolar junction transistor. They have enabled the unprecedented growth in the field of information technology that we see today. Until recently, the technological revolution for better, faster and more efficient devices has been governed by scaling down the device dimensions following Moore's Law. With the slowing of Moore's law, there is a need for alternative materials and computing technologies that can continue the advancement in functionality. Here, we describe a single, dynamically reconfigurable device that implements these three fundamental device functions. The device uses buried gates to achieve n- and p-channels and fits into a larger effort to develop devices with enhanced functionalities, including logic functions, over device scaling. As they are all surface conducting devices, we use one material parameter, the interface trap density of states, to describe the key figure-of-merit of each device.
New concepts and technologies are fast replacing the traditional methods of water distribution, supply and purification. Nanomaterials are well suited for water purification, disinfection and wastewater treatment applications as they have as large specific surface area, high reactivity, high degree of functionalization, size dependent properties, affinity for specific target contaminants, etc. Membranes and filters synthesized using nanomaterials have selective permeability, good flux rates, increased durability, reliability in purification and reusability, and thus are energy saving and cost effective. Various types of nanomaterials such as antimicrobial nanomaterials, carbon nanotubes (CNTs), nanosorbents, dendrimers, self-assembled monolayers on mesoporous silica (SAMMS), single enzyme nanoparticles (SENs), their mechanisms, synthesis and applications are reviewed in this paper. Also, some key issues and challenges are addressed.
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