Nanyang Technological University

About: Nanyang Technological University is a education organization based out in Singapore, Singapore. It is known for research contribution in the topics: Computer science & Catalysis. The organization has 48003 authors who have published 112815 publications receiving 3294199 citations. The organization is also known as: NTU & Universiti Teknologi Nanyang.

Preparation of novel 3D graphene networks for supercapacitor applications

Abstract: The supercapacitor is considered as a promising candidate for energy storage due to its high power performance, long life cycle, and low maintenance cost. [ 3 ] Pseudocapacitive materials, such as transition metal oxides, are being explored for use in supercapacitors with a large specifi c capacitance and high energy density. [ 4 ] However, pseudocapacitors often suffer from the low rate capability and poor stability, because the active materials are usually insulating or semiconducting, which hinders the fast electron transport required for high charge/discharge rates. As an ideal matrix, graphene is commonly used for growth of functional nanomaterials. [ 1a , 2c , 5 ] Recently, nanocomposites made by graphene and transition metal oxides have attracted wide attention in the fi eld of supercapacitors due to their synergetic effect, arising from the combination of the redox reaction of metal oxides with the high surface area/conductivity of graphene, to improve the electrochemical performance. [ 6 ]

Two-dimensional semiconductors for transistors

Abstract: In the quest for higher performance, the dimensions of field-effect transistors (FETs) continue to decrease. However, the reduction in size of FETs comprising 3D semiconductors is limited by the rate at which heat, generated from static power, is dissipated. The increase in static power and the leakage of current between the source and drain electrodes that causes this increase, are referred to as short-channel effects. In FETs with channels made from 2D semiconductors, leakage current is almost eliminated because all electrons are confined in atomically thin channels and, hence, are uniformly influenced by the gate voltage. In this Review, we provide a mathematical framework to evaluate the performance of FETs and describe the challenges for improving the performances of short-channel FETs in relation to the properties of 2D materials, including graphene, transition metal dichalcogenides, phosphorene and silicene. We also describe tunnelling FETs that possess extremely low-power switching behaviour and explain how they can be realized using heterostructures of 2D semiconductors. Field-effect transistors (FETs) with semiconducting channels made from 2D materials are known to have fewer problems with short-channel effects than devices comprising 3D semiconductors. In this Review, a mathematical framework to evaluate the performance of FETs is outlined with a focus on the properties of 2D materials, such as graphene, transition metal dichalcogenides, phosphorene and silicene.

Topological-insulator-based terahertz modulator

Abstract: Three dimensional topological insulators, as a new phase of quantum matters, are characterized by an insulating gap in the bulk and a metallic state on the surface. Particularly, most of the topological insulators have narrow band gaps, and hence have promising applications in the area of terahertz optoelectronics. In this work, we experimentally demonstrate an electronically-tunable terahertz intensity modulator based on Bi1:5Sb0:5Te1:8Se1:2 single crystal, one of the most insulating topological insulators. A relative frequency-independent modulation depth of ~62% over a wide frequency range from 0.3 to 1.4 THz has been achieved at room temperature, by applying a bias current of 100 mA. The modulation in the low current regime can be further enhanced at low temperature. We propose that the extraordinarily large modulation is a consequence of thermally-activated carrier absorption in the semiconducting bulk states. Our work provides a new application of topological insulators for terahertz technology.