Terahertz Biomedical and Healthcare Technologies

Materials to Devices

Amit Banerjee, Basabi Chakraborty, Hiroshi Inokawa, Jitendra Nath Roy

• Publisher: Elsevier
• Year: 2020
• Print ISBN: 9780128185568
• eBook ISBN: 9780128185575
• Topic: Technology & Engineering
• Subtopic: Electrical Engineering & Telecommunications
• Index: Technology & Engineering

Terahertz Biomedical and Healthcare Technologies: Materials to Devices reviews emerging advances in terahertz biomedical and healthcare technologies, including advances in fundamental materials science research, device design and fabrication, applications, and challenges and opportunities for improved performance. In addition, the improvement of materials, optical elements, and measuring techniques are also explored. Other sections cover the design and development of wide bandgap semiconductors for terahertz device applications, including their physics, device modeling, characterization and fabrication concepts. Finally, the book touches on potential defense, medical imaging, internet of things, and the machine learning applications of terahertz technologies.- Reviews the latest advances in the fundamental and applied research of terahertz technologies, covering key topics in materials science, biomedical engineering and healthcare informatics- Includes applications of terahertz technologies in medical imaging, diagnosis and treatment- Provides readers with an understanding of the machine learning, pattern recognition, and data analytics research utilized to enhance the effectiveness of terahertz technologies

section I

TERAHERTZ DETECTORS AND SOURCES: DESIGN AND FABRICATION ASPECTS

Outline

Chapter 1. THz Solid-State Source Based on IMPATT Devices

Chapter 2. Terahertz Sources Based on Difference-Frequency Generation for Spectroscopy and Biomaterial Analysis

Chapter 3. Advanced Materials and Structures for Terahertz Engineering

Chapter 4. 2D Materials as THz Generators, Detectors, and Modulators: Potential Candidates for Biomedical Applications

Chapter 5. Terahertz Technology–Emerging Trends and Application Viewpoints

Chapter 1: THz Solid-State Source Based on IMPATT Devices

Suranjana Banerjee, PhD, MTech, BTech, BSc

Abstract

In recent years, a lot of research interest has been generated for the research and development of terahertz (THz) components, sources, and detectors because of their various applications in astronomy, spectroscopy, bioimaging, biosensing, quality inspection in industrial products, and medical and pharmaceutical research areas. The potentiality of impact avalanche transit time (IMPATT) devices made of different semiconductors particularly the wide bandgap (WBG) semiconductors has been presented in this chapter for operation at THz frequency band. The suitability of IMPATTs based on both normal bandgap (Si, GaAs, InP) and WBG semiconductors (Wz-GaN, 4H-SiC, type IIb diamond) as potential THz sources has been studied by avalanche response time analysis. The design, modelling, and simulation of double-drift region (DDR) IMPATTs based on various semiconductors for operation of these devices at millimetre wave window frequencies (94, 140, 220 GHz) and THz frequency frequencies (0.5, 1.0, 1.5 THz) have also been presented in this chapter. The avalanche resonance limited frequencies of DDR IMPATTs based on GaN, diamond, and Si IMPATTs are found to be 1.00, 1.50, and 0.50 THz, respectively. DDR diamond IMPATTs can be used as potential THz sources to deliver sufficient power at 1.5 THz and above. The simulation provides the avalanche resonance limited frequencies of DDR IMPATTs, which is highest for Wz-GaN in THz band. IMPATT devices based on Wz-GaN are found to be without any competition above 1 THz as regard to delivering high power with high conversion efficiency. A quantum drift-diffusion model based on density gradient theory has been presented for accurate large-signal simulation of DDR IMPATT devices based on conventional and WBG semiconductors operating at higher mm-wave and lower THz frequencies. It is observed that the mm-wave and THz performance of DDR IMPATTs based on Wz-GaN, InP, C, 4H-SiC, and Si are affected by quantum phenomena such as quantum confinement, quantum tunneling, etc., arising at certain limiting frequency. The quantum effect on the large-signal properties of IMPATTs will be appreciable if the dimension of the active layer of the device is of the order of de Broglie wavelength of electrons or holes at the design frequencies in mm-wave and THz bands. However, more accurate prediction of large signal power and conversion efficiency of the device can be made due to incorporation of quantum corrections in the drift-diffusion model. In conclusion, the great potential of Wz-GaN and type IIb diamond as base materials of DDR IMPATTs can be explored to experimentally realize these devices for THz operation

Keywords

Double-drift region (DDR); Impact avalanche transit time (IMPATT); Terahertz (THz); Wide bandgap (WBG)

Introduction

The terahertz (THz) region of the electromagnetic spectrum lies between the traditional millimeter wave and optical bands in the frequency range of 0.1–10 THz and wavelength range of 3–0.03 mm. It is also popularly called “THz gap” lying between microwave and infrared frequency band as shown in Fig. 1.1. THz science and technology are attracting the attention of researchers in recent times mainly due to the emergence of time-domain spectroscopy using pulse laser of extremely narr...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributors
• About the Editors
• section I. TERAHERTZ DETECTORS AND SOURCES: DESIGN AND FABRICATION ASPECTS
• section II. ADVANCED MEDICAL IMAGING, PATTERN RECOGNITION AND TOMOGRAPHIC RECONSTRUCTION
• Index