Design and optimization of high-performance microring-based uni-traveling carrier photodiode for WDM optical systems

In this work, the compressive buckling of a nanowire partially bonded to an elastomeric substrate is studied via finite-element method (FEM) simulations and experiments. The buckling profile of the nanowire can be divided into three regimes, i.e., the in-plane buckling, the disordered buckling in the out-of-plane direction, and the helical buckling, depending on the constraint density between the nanowire and the substrate. The selection of the buckling mode depends on the ratio d/h, where d is the distance between adjacent constraint points and h is the helical buckling spacing of a perfectly bonded nanowire. For d/h > 0.5, buckling is in-plane with wavelength λ = 2d. For 0.27 < d/h < 0.5, buckling is disordered with irregular out-of-plane displacement. While, for d/h < 0.27, buckling is helical and the buckling spacing gradually approaches to the theoretical value of a perfectly bonded nanowire. Generally, the in-plane buckling induces smaller strain in the nanowire, but consumes the largest space. Whereas the helical mode induces moderate strain in the nanowire, but takes the smallest space. The study may shed useful insights on the design and optimization of high-performance stretchable electronics and three-dimensional complex nanostructures.

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Defect Engineering in 2D Materials: Precise Manipulation and Improved Functionalities

Research ◽

10.34133/2019/4641739 ◽

2019 ◽

Vol 2019 ◽

pp. 1-14 ◽

Cited By ~ 10

Author(s):

Jie Jiang ◽

Tao Xu ◽

Junpeng Lu ◽

Litao Sun ◽

Zhenhua Ni

Keyword(s):

High Performance ◽

2D Materials ◽

Optoelectronic Devices ◽

Deep Understanding ◽

Building Blocks ◽

Research Progress ◽

Defect Engineering ◽

Plasma Chemical ◽

Design And Optimization ◽

Novel Structure

Two-dimensional (2D) materials have attracted increasing interests in the last decade. The ultrathin feature of 2D materials makes them promising building blocks for next-generation electronic and optoelectronic devices. With reducing dimensionality from 3D to 2D, the inevitable defects will play more important roles in determining the properties of materials. In order to maximize the functionality of 2D materials, deep understanding and precise manipulation of the defects are indispensable. In the recent years, increasing research efforts have been made on the observation, understanding, manipulation, and control of defects in 2D materials. Here, we summarize the recent research progress of defect engineering on 2D materials. The defect engineering triggered by electron beam (e-beam), plasma, chemical treatment, and so forth is comprehensively reviewed. Firstly, e-beam irradiation-induced defect evolution, structural transformation, and novel structure fabrication are introduced. With the assistance of a high-resolution electron microscope, the dynamics of defect engineering can be visualized in situ. Subsequently, defect engineering employed to improve the performance of 2D devices by means of other methods of plasma, chemical, and ozone treatments is reviewed. At last, the challenges and opportunities of defect engineering on promoting the development of 2D materials are discussed. Through this review, we aim to build a correlation between defects and properties of 2D materials to support the design and optimization of high-performance electronic and optoelectronic devices.

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Self-Screening of the polarized electric field in Wurtzite Gallium Nitride along [0001] direction

Chinese Physics B ◽

10.1088/1674-1056/ac4746 ◽

2021 ◽

Author(s):

Qiu-Ling Qiu ◽

Shi-Xu Yang ◽

Qian-Shu Wu ◽

Cheng-Lang Li ◽

Qi Zhang ◽

...

Keyword(s):

Electric Field ◽

Computer Aided Design ◽

High Performance ◽

High Electron Mobility Transistors ◽

High Electron ◽

Screening Effect ◽

White Leds ◽

Design And Optimization ◽

Electron Mobility Transistors ◽

Dimensional Electron Gas

Abstract The strong polarization effect of GaN-based materials is widely used in high-performance devices such as white-light-emitting diodes (white LEDs), high electron mobility transistors (HEMTs) and GaN Polarization SuperJunctions. However, the current researches on the polarization mechanism of GaN-based materials are not sufficient. In this paper, we studied the influence of polarization on electric field and energy band characteristics of Ga-face GaN bulk materials by using a combination of theoretical analysis and semiconductor technology computer-aided design (TCAD) simulation. The self-screening effect in Ga-face bulk GaN under ideal and non-ideal conditions is studied respectively. We believe that the formation of high-density two-dimensional electron gas (2DEG) in GaN is the accumulation of screening charges. So that, we also clarify the source and accumulation of the screening charges caused by the GaN self-screening effect in this paper and aim to guide the design and optimization of high-performance GaN-based devices.

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Design and Optimization of an Integrated Turbo-Generator and Thermoelectric Generator for Vehicle Exhaust Electrical Energy Recovery

Energies ◽

10.3390/en12163134 ◽

2019 ◽

Vol 12 (16) ◽

pp. 3134 ◽

Cited By ~ 3

Author(s):

Prasert Nonthakarn ◽

Mongkol Ekpanyapong ◽

Udomkiat Nontakaew ◽

Erik Bohez

Keyword(s):

Diesel Engines ◽

High Performance ◽

Thermoelectric Generator ◽

Waste Heat ◽

Electrical Energy ◽

Vehicle Exhaust ◽

Gasoline Engines ◽

Design And Optimization ◽

Charging Station ◽

Turbo Generator

The performance of turbo-generators significantly depends on the design of the power turbine. In addition, the thermoelectric generator can convert waste heat into another source of energy. This research aims to design and optimize an integrated turbo-generator and thermoelectric generator for diesel engines. The goal is to generate electricity from the vehicle exhaust gas. Electrical energy is derived from generators using the flow, pressure, and temperature of exhaust gases from combustion engines and heat-waste. In the case of turbo-generators and thermoelectric generators, the system automatically adjusts the power provided by an inverter. Typically, vehicle exhausts are discarded to the environment. Hence, the proposed conversion to electrical energy will reduce the alternator charging system. This work focuses on design optimization of a turbo-generator and thermoelectric generator for 2500 cc. diesel engines, due to their widespread usage. The concept, however, can also be applied to gasoline engines. Moreover, this model is designed for a hybrid vehicle. Charging during running will save time at the charging station. The optimization by variable van angles of 40°, 50°, 62°, 70°, and 80° shows that the best output power is 62°, which is identical to that calculated. The maximum power outputted from the designed prototype was 1262 watts when operating with an exhaust mass flow rate of 0.1024 kg/s at 3400 rpm (high performance of the engine). This research aims to reduce fuel consumption and reduce pollution from the exhaust, especially for hybrid vehicles.

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