Interaction between terahertz photons and electron waves in quantum structures and its application to ultra-high frequency devices

本研究旨在实现一种基于光子辅助隧穿和传输电子波拍频的新型三端电子器件，用于放大未开发的太赫兹频率范围。研究结果如下：选择了半导体-绝缘体和半导体-金属-绝缘体异质结构体系(CaF2/CdF2/Si和CoSi2/CaF2/Si)作为太赫兹器件的材料，并对其外延生长和器件形成进行了研究。这些材料体系在高势垒和由此形成的尖锐量子能级的观点上是有利的，这有利于高速响应。通过发展包括纳米区局域外延在内的外延生长技术和优化的热处理条件，首次在Si(10 0)衬底上制备了CaF_2/Cd_2/Si共振隧穿二极管(RTD)，并首次在室温下获得了极高的峰谷比(10^6)。…是一种平面二维电致伸缩器件为了验证该器件的工作原理，制作了作为三端太赫兹器件的基本组成部分的半导体层中的气体结构。在毫米波范围内的工作与理论预测一致。在上述研究的基础上，提出了由RTD和小尺寸太赫兹天线组成的集成太赫兹器件结构。作为将该结构应用于金属-绝缘体-半导体异质结的第一步，制作了具有半导体异质结的RTD，并与小尺寸平面天线集成。该器件在室温下以简谐振荡方式振荡，频率为1.02 THz。这是迄今为止室温单电子振荡器的最高频率记录，也是第一个超过1THz频率的记录，尽管它是简谐振荡。此外，通过对器件结构的优化，也证明了基频振荡在2 THz以上是可行的。这些结果不仅表明，即使是具有这种结构的半导体RTD也可以作为紧凑型相干太赫兹源的候选者，而且这种集成结构也可以应用于所提出的金属-绝缘体-半导体系统的太赫兹器件。较少

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 … More 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