Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.

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Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.

A very sensitive photodector based on molybdenum disulphide with potential for integrated optoelectronic circuits, light sensing, biomedical imaging, video recording or spectroscopy is now demonstrated.

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Ultrasensitive photodetectors based on monolayer MoS2.

Graphene’s success has shown that it is possible to create stable, single and few-atom-thick layers of van der Waals materials, and also that these materials can exhibit fascinating and technologically useful properties. Here we review the state-of-the-art of 2D materials beyond graphene. Initially, we will outline the different chemical classes of 2D materials and discuss the various strategies to prepare single-layer, few-layer, and multilayer assembly materials in solution, on substrates, and on the wafer scale. Additionally, we present an experimental guide for identifying and characterizing single-layer-thick materials, as well as outlining emerging techniques that yield both local and global information. We describe the differences that occur in the electronic structure between the bulk and the single layer and discuss various methods of tuning their electronic properties by manipulating the surface. Finally, we highlight the properties and advantages of single-, few-, and many-layer 2D materials in...

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Progress, Challenges, and Opportunities in Two-Dimensional Materials Beyond Graphene

Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocat...

Recent Advances in Ultrathin Two-Dimensional Nanomaterials

Graphene and other two-dimensional materials, such as transition metal dichalcogenides, have rapidly established themselves as intriguing building blocks for optoelectronic applications, with a strong focus on various photodetection platforms The versatility of these material systems enables their application in areas including ultrafast and ultrasensitive detection of light in the ultraviolet, visible, infrared and terahertz frequency ranges These detectors can be integrated with other photonic components based on the same material, as well as with silicon photonic and electronic technologies Here, we provide an overview and evaluation of state-of-the-art photodetectors based on graphene, other two-dimensional materials, and hybrid systems based on the combination of different two-dimensional crystals or of two-dimensional crystals and other (nano)materials, such as plasmonic nanoparticles, semiconductors, quantum dots, or their integration with (silicon) waveguides

http://www-g.eng.cam.ac.uk/nms/publications/pdf/nnano.2014.215.pdf

Photodetectors based on graphene, other two-dimensional materials and hybrid systems

We report on the effect of oxygen plasma treatment of two-dimensional multilayer MoS2 crystals on the subsequent growth of Al2O3 and HfO2 films, which were formed by atomic layer deposition (ALD) using trimethylaluminum and tetrakis-(ethylmethylamino)hafnium metal precursors, respectively, with water oxidant. Due to the formation of an ultrathin Mo-oxide layer on the MoS2 surface, the surface coverage of Al2O3 and HfO2 films was significantly improved compared to those on pristine MoS2, even at a high ALD temperature. These results indicate that the surface modification of MoS2 by oxygen plasma treatment can have a major impact on the subsequent deposition of high-k thin films, with important implications on their integration in thin film transistors.

Improved growth behavior of atomic-layer-deposited high-k dielectrics on multilayer MoS2 by oxygen plasma pretreatment.

This paper presents ultrathin and highly sensitive input/output devices consisting of a capacitive touch sensor (Cap-TSP) integrated on thin-film-encapsulated active-matrix organic light-emitting diodes (OLEDs). The optimal structure of the electrically noise-free capacitive touch sensor, which is assembled on a thin-film-encapsulated active-matrix OLED (AMOLED) display, is obtained by investigating the internal electrical field distribution and capacitance change based on the Q3D Extractor model. Electrostatic simulations have verified malfunction-free electrical signals for 4-in diagonal-sized capacitive touch sensors on AMOLEDs possessing a 100-μm-thick optically clear adhesive (OCA, er = 1.4) layer. The prototype OLED platform using the capacitive touch sensors exhibits an overall thickness of 1.2 mm, which is the lowest thickness for commercially available OLED platforms.

A Highly Sensitive Capacitive Touch Sensor Integrated on a Thin-Film-Encapsulated Active-Matrix OLED for Ultrathin Displays

Local-gate multilayer MoS2 phototransistors exhibit a photoresponsivity of up to 342.6 A W(-1) , which is higher by 3 orders of magnitude than that of global-gate multilayer MoS2 phototransistors. These simulations indicate that the gate underlap is critical for the enhancement of the photoresponsivity. These results suggest that high photoresponsivity can be achieved in indirect-bandgap multilayer MoS2 phototransistors by optimizing the optoelectronic design.

Giant Photoamplification in Indirect‐Bandgap Multilayer MoS2 Phototransistors with Local Bottom‐Gate Structures

Well‐Oriented Silicon Thin Films with High Carrier Mobility on Polycrystalline Substrates

The adaptive and powerful coding schemes in H.264 provide significant coding efficiency and some additional merits like error resilience and network friendliness. In spite of these outstanding features, it is not easy to implement H.264 codec as a real-time system due to its high requirement of memory bandwidth and intensive computation. Although the variable block size motion compensation using multiple reference frames is one of the key coding tools to bring about its main performance gain, it demands substantial computational complexity due to exhaustive search among all possible combinations of coding modes. Many existent fast motion estimation algorithms are not suitable for H.264 having variable motion block sizes. In this paper, we propose the motion field adaptive search using the hierarchical block structure based on the diamond search applicable to variable motion block sizes.

Woong Choi

Papers

Improved growth behavior of atomic-layer-deposited high-k dielectrics on multilayer MoS2 by oxygen plasma pretreatment.

A Highly Sensitive Capacitive Touch Sensor Integrated on a Thin-Film-Encapsulated Active-Matrix OLED for Ultrathin Displays

Giant Photoamplification in Indirect‐Bandgap Multilayer MoS2 Phototransistors with Local Bottom‐Gate Structures

Well‐Oriented Silicon Thin Films with High Carrier Mobility on Polycrystalline Substrates

Fast motion estimation with modified diamond search for variable motion block sizes