Chemically Tuned p‐ and n‐Type WSe2 Monolayers with High Carrier Mobility for Advanced Electronics

Monolayers of transition metal dichalcogenides (TMDCs) have attracted a great interest for post‐silicon electronics and photonics due to their high carrier mobility, tunable bandgap, and atom‐thick 2D structure. With the analogy to conventional silicon electronics, establishing a method to convert TMDC to p‐ and n‐type semiconductors is essential for various device applications, such as complementary metal‐oxide‐semiconductor (CMOS) circuits and photovoltaics. Here, a successful control of the electrical polarity of monolayer WSe₂ is demonstrated by chemical doping. Two different molecules, 4‐nitrobenzenediazonium tetrafluoroborate and diethylenetriamine, are utilized to convert ambipolar WSe₂ field‐effect transistors (FETs) to p‐ and n‐type, respectively. Moreover, the chemically doped WSe₂ show increased effective carrier mobilities of 82 and 25 cm² V^?1s^?1 for holes and electrons, respectively, which are much higher than those of the pristine WSe₂. The doping effects are studied by photoluminescence, Raman, X‐ray photoelectron spectroscopy, and density functional theory. Chemically tuned WSe₂ FETs are integrated into CMOS inverters, exhibiting extremely low power consumption ( ≈ 0.17 nW). Furthermore, a p‐n junction within single WSe₂ grain is realized via spatially controlled chemical doping. The chemical doping method for controlling the transport properties of WSe₂ will contribute to the development of TMDC‐based advanced electronics.     

Direct Synthesis of a Self‐Assembled WSe2/MoS2 Heterostructure Array and its Optoelectrical Properties

Functional van der Waals heterojunctions of transition metal dichalcogenides are emerging as a potential candidate for the basis of next‐generation logic devices and optoelectronics. However, the complexity of synthesis processes so far has delayed the successful integration of the heterostructure device array within a large scale, which is necessary for practical applications. Here, a direct synthesis method is introduced to fabricate an array of self‐assembled WSe₂/MoS₂ heterostructures through facile solution‐based directional precipitation. By manipulating the internal convection flow (i.e., Marangoni flow) of the solution, the WSe₂ wires are selectively stacked over the MoS₂ wires at a specific angle, which enables the formation of parallel‐ and cross‐aligned heterostructures. The realized WSe₂/MoS₂‐based p–n heterojunction shows not only high rectification (ideality factor: 1.18) but also promising optoelectrical properties with a high responsivity of 5.39 A W^?1 and response speed of 16 µs. As a feasible application, a WSe₂/MoS₂‐based photodiode array (10 × 10) is demonstrated, which proves that the photosensing system can detect the position and intensity of an external light source. The solution‐based growth of hierarchical structures with various alignments could offer a method for the further development of large‐area electronic and optoelectronic applications.     

HEVC-based three-layer texture and depth coding for lossless synthesis in 3D video coding

Multimedia Tools and Applications - Efficient lossless coding of a texture image and its corresponding depth map is important to perform accurate view synthesis in 3D applications. In this paper, a...     

Formal or informal human collaboration approach to maritime safety using FRAM

Cognition, Technology & Work - It has been argued that human and organizational factors are critical for accident analysis and safety management. The maritime domain represents a...     

The effects of self-efficacy,self-regulation and social presence on learning engagement in a large university class using flipped Learning

Flipped learning recently gained attention as an effective instructional approach to enhance learning engagement, causing many universities to implement it. To enhance student engagement in large university classes, this study examined the effects of self-efficacy, self-regulation and social presence on learning engagement in a large university class using a flipped learning approach. A total of 390 undergraduates who were enrolled in a large general education class using flipped learning at a university in Korea participated in this study. The learners completed an online survey measuring the variables of this study. The research findings indicated that self-regulation affected social presence as well as learning engagement. Self-efficacy affected social presence and indirectly affected learning engagement through social presence. Finally, social presence affected learning engagement. Social presence also mediated the relationship between self-efficacy and learning engagement as well as between self-regulation and learning engagement. This study confirmed the significant effects of self-regulation and social presence on students' learning engagement in large university classes.     

Optical system design for light detection and ranging with ultra-wide field-of-view using liquid lenses

The light detection and ranging (LiDAR) technology is based on irradiating near-infrared light and measuring the time-of-flight of the scattered light in an object. This technology is becoming increasingly important, as the requirement of three-dimensional camera technology for future autonomous vehicles is on the rise. In this study, we propose an ultra-wide field-of-view (FOV) optical system for LiDAR that can sequentially scan a beam emitted from a high power laser through a small beam steering system using a liquid lens and a fisheye lens. The proposed optical system consists of a series of liquid lenses for beam steering, a commercial fisheye lens with a wide FOV, and a relay optics to effectively conjugate the intermediate image planes of the two lens systems. To verify theoretical feasibility, we have designed a practical optical system with an FOV of approximately 170°, which is much higher than the FOVs in any other non-rotating LiDAR systems.

     

The impact of technology capability,human resources,internationalization, market resources,and customer satisfaction on annual sales growth rates of Korean software firms

This study investigates the competitive factors of software firms that participated in the Korea Software Firm Competitiveness Awards, a nationwide project supported by the Ministry of Knowledge Economy that studies the performance of software firms in Korea. The study applies concepts from hierarchical multiple regression analysis to develop a model to assess the relationship between the competitive factors of software firms and firm performance. The developed model was validated through a field survey of 79 software firms in Korea. The survey results show a significant relationship between competitive factors and firm performance, as well as the relative influence of significant variables. The findings provide two important implications: first, from a management perspective, software firms in Korea focus on human resources based on technology development in the domestic market, and second, from a policy perspective, the government supports the establishment of external capabilities (internationalization and partnerships) for software firms. These findings are available to researchers, policy makers, software developers, and other market players, and contribute to the literature on the importance of competitive factors.     

A Hybrid Staggered Discontinuous Galerkin Method for KdV Equations

A hybrid staggered discontinuous Galerkin method is developed for the Korteweg–de Vries equation. The equation is written into a system of first order equations by introducing auxiliary variables. Two sets of finite element functions are introduced to approximate the solution and the auxiliary variables. The staggered continuity of the two finite element function spaces gives a natural flux condition and trace value on the element boundaries in the derivation of Galerkin approximation. On the other hand, to deal with the third order derivative term an hybridization idea is used and additional flux unknowns are introduced. The auxiliary variables can be eliminated in each element and the resulting algebraic system on the solution and the additional flux unknowns is solved. Stability of the semi discrete form is proven for various boundary conditions. Numerical results present the optimal order of \(L^2\)-errors of the proposed method for a given polynomial order.     

An Identification of Factors Motivating Individuals’ Use of Cloud-Based Services

The purpose of this study is to develop a better understanding of the factors motivating individuals who use cloud-based services despite the privacy and security risks associated with it. The authors developed a research model that incorporates the theory of planned behavior (TPB) and constructs from previous research to explain individuals’ intentions to use cloud-based services. Our analysis shows support for the relationships among predictor variables (attitude, subjective norm, perceived behavioral control, and information privacy) and the outcome variable (behavioral intention). Additionally, our analysis shows IT leadership and trust as moderating variables between the TPB predictor variables (attitude and perceived behavioral control), but not subjective norm. The results indicate that IT leadership support of cloud-based systems can have a positive effect on cloud adoption and individuals are likely to continue their use of cloud computing despite the privacy and security risks associated with it.     

Experimental study of electro-hydraulic actuator with payload for precision motion control

Microsystem Technologies - Offline iterative control technique in a hydraulic testing sector is primarily used to improve the tracking control performance despite nonlinearity caused by a testing...