Review of GaN-based devices for terahertz operation

Abstract

Abstract. GaN provides the highest electron saturation velocity, breakdown voltage, operation temperature, and thus the highest combined frequency-power performance among commonly used semiconductors. The industrial need for compact, economical, high-resolution, and high-power terahertz (THz) imaging and spectroscopy systems are promoting the utilization of GaN for implementing the next generation of THz systems. As it is reviewed, the mentioned characteristics of GaN together with its capabilities of providing high two-dimensional election densities and large longitudinal optical phonon of ∼90 meV make it one of the most promising semiconductor materials for the future of the THz emitters, detectors, mixers, and frequency multiplicators. GaNbased devices have shown capabilities of operation in the upper THz frequency band of 5 to 12 THz with relatively high photon densities in room temperature. As a result, THz imaging and spectroscopy systems with high resolution and deep depth of penetration can be realized through utilizing GaN-based devices. A comprehensive review of the history and the state of the art of GaN-based electronic devices, including plasma heterostructure field-effect transistors, negative differential resistances, hetero-dimensional Schottky diodes, impact avalanche transit times, quantum-cascade lasers, high electron mobility transistors, Gunn diodes, and tera field-effect transistors together with their impact on the future of THz imaging and spectroscopy systems is provided.

Thermographic Non-Destructive Evaluation for Natural Fiber-Reinforced Composite Laminates

“…The electromagnetic spectrum of millimetre-wave generally ranges from 30 GHz to 300 GHz, which has a region of overlap between 100 GHz and 300 GHz with THz spectroscopy [28][29][30]. Compared to pulsed THz imaging which can provide depth, frequency-domain or time-domain information of the object, CW THz imaging can only yield intensity data when a fixed frequency source and a single detector are used.…”

Terahertz spectroscopic estimation of crystallinity of poly(phenylene sulfide)

“…Recently, electromagnetic waves in a frequency range from 0.1 to 10 THz or in a wave number range from 3.3 to 333 cm 21 are called terahertz (THz) waves, and they are attracting keen attention in various fields such as protection of cultural heritage, [11][12][13] inspection of integrated circuits (IC), 14,15 and characterization of composite materials and compounds. [16][17][18][19] In addition, THz absorption spectroscopy has emerged as a new tool for analyzing the structure of matter, since it can detect non-destructively various skeletal vibrations and intermolecular vibrations such as lattice vibrations.…”

Continuous Wave Terahertz Sensing Using GaN HEMTs

“…It has great potential as sensitive and fast operating detectors because of the material properties such as high breakdown voltage, high carrier density, and high values of the electron saturation velocity . High electron density as well as high LO phonon energy of ≈90 meV of GaN based devices make them promising devices for high frequency operation . Recently, new devices based on GaN HEMT with nanoantennas or a resonant cavity were developed, allowing the achievement of noticeable enhancements of the detection responsivity.…”

“…[21] High electron density as well as high LO phonon energy of %90 meV of GaN based devices make them promising devices for high frequency operation. [22,23] Recently, new devices based on GaN HEMT with nanoantennas [24] or a resonant cavity [25] were developed, allowing the achievement of noticeable enhancements of the detection responsivity.…”