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Design of phonon optics devices based on multilayred semiconductor heterostructures of nanometer dimension

基于纳米尺度多层半导体异质结构的声子光学器件设计

基本信息

批准号：
05650002
负责人：
TAMURA Shin-ichiro
金额：
$ 1.34万
依托单位：
Faculty of Engineering Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05650002/
关键词：
Superlattice Phonon THz Time delay Resonance Transmission Nanometer Double barrier TH_Z 障壁共鳴トンネルトンネル時間

项目摘要

Synthetic semiconsuctor heterostructures or superlattices are useful not only for the application to electronic devices of nanometer dimensions but also for the design of various phonon optics devices such as the phonon mirror, the phonon reflector, the phonon resonator, and so on. Stimulated by the idea for fabricating the these devices, we have proposed systems for phonons based on multiple superlattice structures. The key idea is to utilize the fact that in perioid superlattices Bragg reflections occur for long wavelength phonons, or the superlattices act as opaque barriers for phonons within the frequency gaps induced by the periodicity of a superlattice. If a periodicity of a superlattice is 30 A or longer, the lowest frequency gap of phonons is produced in the sub-THz range. The wavelength of 1-THz phonons is typically 30-50 A and their mean free path in pure solids is about 1 mm or longer at low temperatures. Therefore, these high-frequency phonons propagate ballilstically throu … More gh the systems with linear dimensions in the nanometer range.In the present project, we studied the dynamical properties of phonons propagating in superlattices, which had not been discussed before. Explicitly, we studied by numerical simulations the time evolutions of phonon packets incident on the single and double-barrier structures for phonons realized by semiconductor superlattices. In the asymptotic regions far from the barriers both the time delay and advance are observed for the transmitted and reflected packets. To explain these results of the simulations, we developed in the present project, the analytical calculations for the transmission and reflection times associated with the interaction of phonons with one-dimensional elastic barriers composed of periodic superlattices. The exact and useful approximate expressions for the phase times which well describe the delay times for phonon packets narrow in the wave-vectors space were derived. These results provide important information on the dynamical aspect of phonon transmission through superlattices and hence are useful for designing phonon optics devices. Less

合成半导体异质结或超晶格不仅可用于纳米电子器件，还可用于设计各种声子光学器件，如声子镜、声子反射镜、声子谐振器等。受制作这些器件的想法的启发，我们提出了基于多重超晶格结构的声子系统。其关键思想是利用在周期超晶格中，布拉格反射发生在长波声子上，或者超晶格作为声子在由超晶格的周期性引起的频隙内的不透明势垒。如果超晶格的周期为30A或更长，则在亚太赫兹范围内产生最低频隙的声子。1-THz声子的波长通常为30-50A，其在纯固体中的平均自由程在低温下约为1 mm或更长。因此，这些高频声子通过…以弹道方式传播在本项目中，我们研究了声子在超晶格中传播的动力学性质，这是以前没有讨论过的。显式地，我们通过数值模拟研究了声子包入射到半导体超晶格实现的声子的单势垒和双势垒结构上的时间演化。在远离障碍物的渐近区域，观察到了传输和反射分组的时延和超前。为了解释这些模拟结果，我们在本项目中发展了与声子与由周期超晶格组成的一维弹性势垒相互作用相关的传输和反射时间的解析计算。给出了波矢空间中描述窄声子包延迟时间的精确而实用的相位时间近似表达式。这些结果提供了声子通过超晶格传输的动力学方面的重要信息，因此对设计声子光学器件是有用的。较少