Abstract- Rainbow Trapping in Highly Doped Silicon Graded Grating Strip at the Terahertz Range

Yan Liu,  Ruoying Kanyang, Genquan Han, Yao Shao, Cizhe Fang ;  Yan Huang,  Siqing Zhang,   Jincheng Zhang

https://ieeexplore.ieee.org/document/8318699/

In this paper, we propose surface plasma polaritons (SPPs) propagating along the structure of grating grooves based on highly doped silicon, which exhibits better performance of exciting SPPs than metal at low frequency (e.g., microwaves, mid infrared, and terahertz). The dispersive properties of the gradient-corrugated grating waveguides are characterized using the computer simulation technology microwave studio. Moreover, the propagation characteristics of the highly doped silicon grating structure are analyzed in detail by the dispersion curves, two-dimensional electric field magnitude distributions, the propagation loss, and the SPP lifetime. It is demonstrated that the gradient-corrugated grating waveguides based on heavily doped silicon could excite SPPs and realize rainbow trapping. The lifetime of the plasmonic mode can reach a value of 1200 ps, which may be long enough for some meaningful nanophotonic applications. The highly doped silicon is an ideal candidate for making practical use of the slow-light system in optical communication and various nanophotonic circuits, which permits further application for compact plasmonic devices.

Abstract-Engineering rainbow trapping and releasing in ultrathin THz plasmonic graded metallic grating strip with thermo-optic material

Yan Liu, Yibo Wang, Genquan Han, Yao Shao, Cizhe Fang, Siqing Zhang, Yan Huang, Jincheng Zhang, and Yue Hao

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-2-1278&origin=search

In this paper, we propose an ultrathin THz plasmonic metallic strip based on graded grating structure with thermo-optic material, which exhibits a strong engineering of trapping and releasing electromagnetic waves in terahertz regimes. The dispersion properties of the ultrathin spoof slow-wave plasmonic graded grating waveguide are characterized using the finite element method, and the propagation characteristics of the grating structures are thoroughly analyzed by the dispersion curves, electric field magnitude distribution, and electric field vertical distribution. The gradient grating waveguide is demonstrated to be an ideal slow-wave system for trapping and releasing surface plasmon polaritons (SPPs) waves through tuning the refractive index of the thermo-optic material. The reflected location for the SPPs waves on the graded corrugated metal strip at 1.1 THz at different temperatures are compared. It is proved that such ultrathin gradient grating waveguide provides an excellent performance for trapping and releasing surface waves at THz, which permits applications for future optical communications.

© 2017 Optical Society of America

Abstract-Dislocation blocking by AlGaN hot electron injecting layer in the epitaxial growth of GaN terahertz Gunn diode

Liang Li, Lin'an Yang, Jincheng Zhang, and Yue Hao

State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, School of Microelectronics, Xidian University, Xi'an 710071, China 

http://jap.aip.org/resource/1/japiau/v114/i10/p104508_s1?isAuthorized=no

This paper reports an efficient method to improve the crystal quality of GaN Gunn diode with AlGaN hot electron injecting layer (HEI). An evident reduction of screw dislocation and edge dislocation densities is achieved by the strain management and the enhanced lateral growth in high temperature grown AlGaN HEI layer. Compared with the top hot electron injecting layer (THEI) structure, the bottom hot electron injecting layer (BHEI) structure enhances the crystal quality of transit region due to the growth sequence modulation of HEI layer. A high Hall mobility of 2934 cm²/Vs at 77 K, a nearly flat downtrend of Hall mobility at the temperature ranging from 300 to 573 K, a low intensity of ratio of yellow luminescence band to band edge emission, a narrow band edge emission line-width, and a smooth surface morphology are observed for the BHEI structural epitaxy of Gunn diode, which indicates that AlGaN BHEI structure is a promising candidate for fabrication of GaN Gunn diodes in terahertz regime.

© 2013 AIP Publishing LLC

Article Outline

1. INTRODUCTION
2. EPITAXIAL GROWTH
3. MEASUREMENTS AND DISCUSSIONS
   1. TEM characterization
   2. HRXRD characterization
   3. High/low temperature-dependent Hall characterization
   4. PL characterization
   5. AFM characterization
4. CONCLUSION