Abstract-Thermal Modeling of the GaN-based Gunn Diode at Terahertz Frequencies

Ying Wang,  Jinping Ao,  Shibin Liu,  Yue Hao,

https://www.mdpi.com/2076-3417/9/1/75

In this paper, a comprehensive evaluation of thermal behavior of the GaN vertical n⁺-n⁻-n-n⁺ Gunn diode have been carried out through simulation method. We explore the complex effects of various parameters on the device thermal performance through a microscopic analysis of electron movements. These parameters include operation bias, doping level, and length of the active region. The increase of these parameters aggravates the self-heating effect and degrades the electron domains, which therefore reduces the overall performance output of the diode. However, appropriate increase of the doping level of active region makes the lattice heat distribute more uniformly and improves the device performance. For the first time, we propose the transition domain, which is in between the dipole domain and accumulation layer, and stands for the degradation of the electron domain. We have also demonstrated that dual domains occur in the device with longer active region length and higher doping level under EB (Energy balance) model, which enhances the harmonics component. Electric and thermal behaviors analysis of GaN vertical Gunn diode makes it possible to optimize the device.

Abstract-Finger print sensor molding thickness none destructive measurement with Terahertz technology

Longhai Liu ;  Haitao Jiang ;  Ying Wang ;  Qinghua Shou ;  Jianhua Xie ;  Yaqi Lu

http://ieeexplore.ieee.org/document/7919842/

Fingerprint sensor (FPS) becomes rapidly popular due to small size and high safety. The molding thickness of capacitive FPS will affect its performance and needs to be accurately measured and controlled. Different from cutting and laser drilling method, one none destructive method with Terahertz electromagnetic wave is introduced. Terahertz wave can penetrate into the molding package materials. The molding thickness can be measured through time delay of two pulse Terahertz waves. The measured thickness is correlated with microscope view and the result is within ±4um gap.

Abstract-The terahertz characteristics of a sandwich type microplasma structure

Ruilin Gao¹, Chengxun Yuan¹, Ying Wang¹, Zhongxiang Zhou¹, Dewei Gong¹, Yuan Fang¹, and Xianwei Rong²

¹Department of Physics, Harbin Institute of Technology, Harbin, Heilongjiang 150001, China
²School of Physics and Electronic Engineering, Harbin Normal University, Harbin, Heilongjiang 150025, China 

http://jap.aip.org/resource/1/japiau/v114/i12/p123302_s1?isAuthorized=no

Recently, major technical advances in developing intense terahertz (THz) sources have provided us with new opportunities to investigate characteristics of a high density microplasma with THz waves. In this paper, a simple sandwich type microplasma model is established. The finite-difference time-domain method using Z-transforms is utilized to simulate the characteristics of reflection, transmission, and absorption of THz waves in this microplasma structure. The effects of both the microplasma width and the permittivity of the outer medium on the propagation are analyzed, and the results show that the THz waves can be greatly influenced and modulated by the structure of the plasma slab and the outer medium. It is demonstrated that such plasma metamaterials exhibit some extraordinary properties in THz frequency range.

© 2013 AIP Publishing LLC

Article Outline

1. INTRODUCTION
2. FDTD ALGORITHM
   1. Z-transforms FDTD method
   2. Validity and precision of Z-transforms FDTD
3. SIMULATION RESULTS AND DISCUSSION
   1. Establishment of the model and choice of the parameters
   2. The effects of plasma layer thickness on the propagation of THz waves
   3. The modulation effects of dielectric plates on the propagation of THz waves
4. CONCLUSION