2005 Fiscal Year Final Research Report Summary
Interaction between terahertz photons and electron waves in quantum structures and its application to ultra-high frequency devices
| Project/Area Number |
15206038
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electron device/Electronic equipment
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
ASADA Massahiro Tokyo Institute of Technology, Interdisciplinary Graduate School of Science and Engineering, Professor, 大学院・総合理工学研究科, 教授 (30167887)
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| Co-Investigator(Kenkyū-buntansha) |
WATANABE Masahiro Tokyo Institute of Technology, Interdisciplinary Graduate School of Science and Engineering, Associate Professor, 大学院・総合理工学研究科, 助教授 (00251637)
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| Project Period (FY) |
2003 – 2005
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| Keywords | terahertz devices / resonant tunneling structures / metal-insulator-semiconductor quantum structures / CaF2 / CdF2 / Si / CoSi2 / CaF2 / Si / nano-area local epitaxy / integrated terahertz antennas / terahertz harmonic oscillation / 集積テラヘルツアンテナ / 高調波テラヘルツ発振 |
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| Research Abstract |
This research aimed at realization of a novel three-terminal electron device based on photon-assisted tunneling and beat of transit electron waves for amplification of undeveloped terahertz frequency range. The results obtained are as follows.
Semiconductor-insulator and semiconductor-metal-insulator heterostructure systems (CaF2/CdF2/Si and CoSi2/CaF2/Si) were chosen for the materials of the terahertz devices, and epitaxial growth and device formation are investigated. These material systems are advantageous in the view point of high potential barrier and resulting formation of sharp quantum levels which are convenient for high speed response. By the development of epitaxial growth technique including nano-area local epitaxy and optimized annealing conditions, resonant tunneling diodes (RTDs) with CaF2/CdF2/Si on Si(100) substrate were fabricated and operated with extremely high peak-valley ratio of 10^6 at room temperature for the first time.
A planar device with two-dimensional electr
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on gas in semiconductor layer structure, which is a basic part of the proposed three-terminal terahertz device, was fabricated to confirm the principle operation of the proposed device. The operation in the millimeter wavelength range was in agreement with theoretical prediction. The operation even in the terahertz range was also expected form this result.
Together with the above researches, integrated terahertz device structure composed of RTDs and small-size terahertz antennas is proposed. As the first step to apply this structure to metal-insulator-semiconductor heterostructures, RTDs with semiconductor heterosturcutre was fabricated and integrated with small-size planar antennas. This device oscillated at 1.02THz with harmonic oscillation mode at room temperature. This is the highest frequency record, as well as the first over-1THz frequency, of a room-temperature single electronic oscillator to date, although it is the harmonic oscillation. Further more, it was also shown that oscillation over 2THz with fundamental frequency mode was feasible with the optimization of the device structure. These results showed not only that even semiconductor RTD with this structure can be a candidate for compact and coherent terahertz sources but also that this structure of integration can be applied to the proposed terahertz device with metal-insulator-semiconductor system. Less
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