發展針對二維材料電晶體的自洽求解非平衡態格林函數耦合泊松方程式之量子傳輸數值模擬軟體

Development of Self-Consistent Poisson-NEGF Quantum Transport Simulator for 2D Material-Based Transistor

林稚皓(Jhih-Hao Lin)

指導教授 ： 吳育任

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202000415

摘要

近年來，隨著金氧半場效電晶體的柵極長度縮小到20奈米以下，因為量子特性沒有被考慮在內的關係，導致傳統的載子傳輸模擬系統，像是漂移擴散模型，無法準確描述載子的傳輸行為。因此，像是能夠考慮載子波特性的非平衡格林函數量子傳輸模擬軟體，對我們研究載子傳輸問題有其存在的意義。在此研究中，我們開發了一個能夠計算在二維材料電晶體中的電子-聲子散射、摻雜離子散射和遠程聲子散射的非平衡格林函數與泊松方程式耦合的自洽求解二維量子傳輸模擬軟體來模擬在電晶體中的載子傳輸特性。藉由此模擬，我們可以發現元件的性能主要取決於由周圍材料引起的遠程聲子散射和由通道材料自己引起的電子-聲子散射，以及帶電離子的散射，並且隨著柵極電壓的增加，變形電位散射在電晶體中會變得越來越重要。此外，根據自洽求解的結果，我們可以模擬像是臨界電壓、次臨界擺幅、飽和區以及源極到漏極的穿隧電流等二維材料電晶體的輸出和傳輸特性。最後，本文將對傳統漂移擴散傳輸模型與非平衡格林函數與泊松方程式耦合的自洽求解量子傳輸模型進行比較與討論。

關鍵字

非平衡格林函數 ； 泊松方程式 ； 自洽求解 ； 電子-聲子散射 ； 摻雜離子散射 ； 遠程聲子散射 ； 二維材料 ； 單層二硫化鉬電晶體

並列摘要

In recent years, as the gate length of metal-oxide-semiconductor field-effect transistor scaled down below 20 nm, the traditional carrier transport program such as drift-diffusion model could not accurately describe the behavior of carrier transport since the quantum effects could not be taken into account. To solve this issue, the quantum transport simulator like non-equilibrium Green's function formalism which includes the wave nature of carriers is proposed to study the carrier transport problem. In this thesis, the major focus is to develop a suitable NEGF simulator for two-dimensional (2D) material such as MoS2 and WS2. Therefore, a 2D quantum transport simulator based on self-consistent Poisson-NEGF program is developed to simulate the characteristics of carrier transport with considering the electron-phonon scattering, impurity scattering, and remote phonon scattering in 2D material based transistors. The result shows that the performance of transistor is determined by both the remote phonon scattering caused from the surrounding material and the deformation potential scattering induced from the channel material itself. The deformation potential scattering would be the dominant factor in the transistor as the gate voltage increases. In addition, according to the result of self-consistent Poisson-NEGF program, the electronic properties of output and transfer characteristic of 2D material such as threshold voltage, subthreshold swing, current saturation and the tunneling current from source to drain can be simulated. Finally, the comparison of the traditional Poisson and drift-diffusion transport model and Poisson-NEGF quantum transport program were discussed in this thesis.

並列關鍵字

NEGF Formalism ； Poisson Equation ； Self-Consistent ； Electron-Phonon Scattering ； Ionized Impurity Scattering ； Remote Phonon Scattering ； 2D material ； Monolayer MoS2-Based Field-Effect Transistor

參考文獻

[1] G. Moore, "Cramming more components onto integrated circuits," Electronics, vol. 38, p. 114, 1965.

[2] M. Ieong, B. Doris, J. Kedzierski, K. Rim, and M. Yang, "Silicon device scaling to the sub-10-nm regime," Science, vol. 306, no. 5704, pp. 2057-2060, 2004.

[3] B. Davari, R. H. Dennard, and G. G. Shahidi, "Cmos scaling for high performance and low power-the next ten years," Proceedings of the IEEE, vol. 83, no. 4, pp. 595-606, 1995.

[4] S.-H. Oh, D. Monroe, and J. M. Hergenrother, "Analytic description of short-channel effects in fully-depleted double-gate and cylindrical, surrounding-gate MOSFETs," IEEE Electron Device Letters, vol. 21, no. 9, pp. 445-447, 2000.

[5] K. Roy, S. Mukhopadhyay, and H. Mahmoodi-Meimand, "Leakage current mechanisms and leakage reduction techniques in deep-submicrometer cmos circuits," Proceedings of the IEEE, vol. 91, no. 2, pp. 305-327, 2003.