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ERATO
Exploratory Research for Advanced Technology 
戦略的創造研究推進事業(総括実施型研究)
創造科学犠実推進事業
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HOME > Research Projects > Post Project > NISHIZAWA Terahertz
NISHIZAWA Terahertz
Research Director: Dr. Jun-ichi Nishizawa
(President Tohoku University)
Research Term 1987-1992
 
Project Description
 The main theme of this project was to fill in the technological gap between the submillimeter and infrared wavelengths - the tetrahertz (1012 Hz) region - for the further development of telecommunications and processing. The semiconductor devices and circuits studied in this project will most likely find applications in ultra-high-speed integrated circuits, high-density optical-fiber communication systems, plasma diagnostics, remote sensing, radio astronomy and molecular spectroscopy.

Research Results

Photo-stimulated molecular layer epitaxy (PMLE): Methods were developed to fabricate ultra-thin epitaxial gallium arsenide layers of device quality, being controlled to crystal monolayer precision. This method was applied as both a tool and for the development of electron devices.

Semiconductor Raman laser: A semiconductor Raman laser was developed having attractive characteristics for demodulation in the terahertz frequency region as well as a radiation source for the far-infrared wavelength region.

Ideal static induction transistor (ISIT): As a further development of the static induction transistor (SIT), the ISIT features a channel length shorter than the mean-free-path of electrons with atoms of the crystal lattice. The estimated cut-off frequency is around 800 GHz.

TUNNETT diode: Molecular layer epitaxy was applied to fabricate TUNNETT diodes for generators oscillating up to 500 GHz with semi-coaxial cavities.

Schottky barrier diode (SBD): While studying GaAs detectors, mixers, quasi-optical multi-element imaging arrays and frequency multipliers for measurements in the THz region, a fabrication process was developed for low-conversion-loss, low-noise Pt/GaAs Schottky diodes (0.4-0.8µm diameter).

Quasi-optical imaging arrays: Multi-element, quasi-optical imaging arrays consisting of Yagi antennas and Schottky diodes were developed.

Coherent power combiner: To solve the problem of low power generated at very high frequencies, a coherent power combiner was developed. Together with active elements, such as Gunn diodes or FETs, it is effective at millimeter and shorter wavelengths.

Optical waveguide modulators: Among the important devices used for light transmission, switching and signal processing are optical waveguide modulators. A traveling-wave optical modulator was developed which has the potential of offering a perfect matching of microwave and optical velocities.

graph1

·Performance distribution of integrated circuits

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·Output power and frequency of semiconductor devices

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·Photostimulated Molecular Layer Epitaxy(PMLE)equipment. This novel method enables the molecular layer single crystal growth of semiconductors such as GaAs,AlxGa1-xAs,lnxGa1-x As and Si with illumination of ultraviolet light.

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·Cross-sectional view of the semiconductor Raman laser
 

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Exploratory Research for Advanced Technology 
戦略的創造研究推進事業(総括実施型研究)
創造科学技術推進事業 ERATO