近年來隨著量子電腦與高效能運算的發展，操作於低溫的互補式金氧半場效電晶體越來越受到重視。從過去的文獻中我們已經知道元件特性會隨著降溫而獲得改善，例如較低的漏電流、較陡峭的次臨界擺幅與較高的載子遷移率等等。然而，存在於半導體通道與閘極氧化層介面的帶尾能態會在低溫下顯著地影響元件的特性，而針對這個議題的理論模型尚未完整。因此本研究論文發展了一套模擬流程，使用了分子動力學、第一原理計算與TCAD 模擬，計算帶尾能態的分布情形，並且分析帶尾能態對於元件特性的影響。
首先我們利用分子動力學建構出S i/SiO 2 介面模型，用來代表電晶體內部的半導體通道與閘極氧化層，之後使用第一原理計算分析此模型的帶尾能態，從此結果當中，我們可以再進一步分析帶尾能態在實體空間中的分布情形，以及計算帶尾能態的寬度，最後在TCAD 模擬中加入帶尾模型，並將第一原理計算的結果作為輸入參數，藉由比較元件在不同溫度下的電性表現，了解帶尾能態在低溫時對於元件特性的影響程度。

With the development of quantum computing and high-performance computing in recent years, cryogenic CMOS has attracted much attention. From past literatures, it is known that the device characteristics will be improved with decreasing temperature, for instance, lower leakage current, steeper subthreshold swing, higher carrier mobility, etc. However, the presence of band tail states at the semiconductor-channel/gate-oxide interface affects the electrical characteristics of MOSFETs at low temperatures. And the theoretical analyzer has not been completely constructed yet. Therefore, this study develops a simulation procedure to calculate band tail states and analyze the impact of band tail states on device characteristics by using molecular dynamics, ab initio, and TCAD simulators.
First, we create a Si/SiO2 atomic model by MD simulations to represent the semiconductor-channel/gate-oxide interface structure in a MOSFET. Then, the density of states of the Si/SiO2 model is calculated by ab initio calculations. From this result, we further analyze the spatial distribution of band tail states and calculate the width of band tail states. Lastly, the result obtained by ab initio calculation can be used as input parameters of the band tail model in TCAD simulations. By comparing the electrical performance of MOSFETs at working different temperatures, we can understand the impacts of band tail states on the device characteristics at low temperatures.

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