奈米元件的特殊效應

Novel effects in the nano-scale quantum devices

李祈延(Chi-Yen Li)

指導教授 ： 周志隆 ； 廖森茂

中原大學/工學院/電子工程研究所/碩士(2005年)

https://doi.org/10.6840/cycu200500124

摘要

摘要

隨著電子元件的尺寸縮小至奈米級單位，許多特殊的效應也顯現出來。例如，庫倫阻斷效應 (Coulomb blockade effect) 在毫微米的元件中並不明顯，可以被忽略。但是在奈米尺寸的世界中，上述效應是非常重要且可以用來控制電子的運動。而現今電子科技的技術蓬勃發展，使我們可以製造出各種先進的奈米級量子元件。例如量子波導元件 (quantum waveguide device) 有著體積小、製作簡單的優點，某些功能上可以取代現有元件。
本論文為探討奈米量子元件中的一些特殊效應。首先我們討論在量子井中，穿隧效應 (tunneling effect) 與庫倫阻斷效應的原理。並且利用數值計算模擬出穿隧率 (tunneling rate) 與偏壓 (bias voltage) 的關係。論文的第二部份介紹一維量子線圖 (quantum graph) 的電子散射 (scattering)。量子線圖是由量子波導元件所組合而成，不同幾何形狀的量子線圖，電子的穿透係數 (transmission coefficient) 也不同。由電子穿透率的模擬結果，我們提出由T型量子波導與量子環 (quantum ring) 所組合而成的量子線圖，可以作為一邏輯反向器 (inverter)。

關鍵字

穿隧效應 ； 量子波導 ； 庫倫阻斷效應

並列摘要

Abstract

As the size of the electronic devices shrink down below the nanometer, a lot of spectacular characteristics appear. For example, Coulomb blockade effect is not evident and ignored in the micro-scale devices. On the other hand the Coulomb blockade effect may be used to control the motion of electron in the nano-scale devices. The well-developed nano-technology also allows us to fabricate many kinds of quantum devices that are based on the theory of quantum physics. For example, the quantum waveguide device is very easy to fabricate in laboratory. It has the potential to replace the traditional semiconductor devices with a much smaller size.
In this thesis we discuss novel physical effects in the nano-scale quantum devices. First, we discussed the physics of tunneling and the Coulomb blockade effect in a semiconductor p-i-n quantum well. We calculated the tunneling rates as a function of bias voltage and showed their numerical results. The second part of this thesis devotes to the scattering problem in the one-dimensional quantum graphs. Unlike the potential scattering, anti-resonance could occur in the geometry scattering. This makes the geometry scattering fundamentally different from the potential scattering. The transmission coefficients of electrons in several quantum graphs with different geometries are also calculated. Finally we proposed a device that is the combination of the T-shaped quantum waveguide and the quantum ring. By calculating the electron transmission, we found that the device act as an inverter.

並列關鍵字

quantum waveguide ； Coulomb blockade effect ； tunneling effect

參考文獻

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