高載子遷移率電晶體之電性與能量傳遞模擬

Abstract

氮化鎵有著高崩潰電壓、高電子遷移率和飽和速度，使其成為一個非常適合應用在高功率和高溫的微波上。本論文利用Silvaco軟體模擬氮化鎵高功率電子遷移率電晶體之元件特性，使用晶格熱流公式去探討其熱影響。最後利用數值模擬結果與交通大學材料工程研究所開發的D-mode AlGaN/GaN HEMT元件實驗結果做比較，以梯度法求最小平方誤差，逆運算求出元件的電子遷移率特性參數及壓電效應參數。

經由模擬結果顯示，加入晶格溫度熱效應的考量，電流會隨著汲極電壓上升有一最大飽和電流，之後再隨著汲極電壓上升電流會下降，一般將此現象歸因於電子遷移率隨電場與溫度上升而下降，本論文模擬結果顯示，二維電子氣濃度隨著溫度上升而下降，是造成此現象的可能原因之一。

Gallium nitride is suitable for application in high-power microwave, because of its high breakdown voltage, high electron mobility and saturation velocity. In this thesis, SILVACO is used to simulate I-V characteristics of AlGaN/GaN High Electron Mobility Transistors (HEMT). The lattice heat flow equation is used to investigate the thermal effect. Least square errors between simulation and experiment results were calculated by using the gradient method to estimate mobility and polarization parameters of AlGaN / GaN HEMT devices developed by the Institute of Materials Engineering of National Chiao Tung University.

Simulation results reveal that the current saturates at a maximum value and then decreases with the increase of the drain voltage when lattice thermal effect is considered. This phenomenon is usually attributed to the decrease of the electron mobility with the electric field and the temperature rising. In this thesis, we noticed that the decrease in 2DEG electron concentration with temperature rising is also a reason of the current falling.