高頻磷化銦雙異質接面雙極性電晶體模擬分析與優化

Abstract

由於針對 DHBT 元件的模擬研究文獻相對較少，且模擬過程中對合適參數的設定及模擬功能的使用細節通常未被詳細說明，因此本研究採用實驗室開發的二維元件 TCAD 軟體 DDCC（Drift-Diffusion Carrier Controller）進行模擬研究。我們針對 type I 和 type II DHBT 進行元件參數特性模擬、尺寸微縮預測及磊晶結構的設計與優化。 在參數特性檢驗中，我們發現壓降主要集中在 Base 層及 Base-Collector 連接處的空乏層，而其他區域，如重摻雜磊晶層與 Base-Emitter 接面磊晶層，其壓降與阻抗占比較低。在尺寸微縮預測方面，轉導（gm）主要受 Emitter mesa 寬度及 Base-Emitter 電極間距的影響，而電容（C）則與 pn 接面寬度呈正相關，因為寬度與接面面積成正比。微縮後，type I 和 type II 的最佳 fT 值分別約為 140 GHz 和 450 GHz。為了進一步優化 type I DHBT，我們透過減少空乏層及基極磊晶層厚度，成功將 fT 提升至約 300 GHz。最後，我們探討了基極厚度縮小時，type I 和 type II DHBT 元件特性的差異。

Abstract Due to the relatively limited literature on DHBT device simulations and the lack of detailed explanations regarding suitable parameter settings and the use of simulation functions, this study employs the lab-developed two-dimensional TCAD software DDCC (Drift-Diffusion Carrier Controller) for simulation research. We conducted simulations of device parameter characteristics, size scaling predictions, and epitaxial structure design and optimization for type I and type II DHBTs. In examining parameter characteristics, we found that the voltage drop is primarily concentrated in the base layer and the depletion region at the Base-Collector junction, whereas other areas, such as heavily doped epitaxial layers and Base-Emitter junction epitaxial layers, exhibit lower voltage drops and impedance proportions. For size scaling predictions, transconductance (gm) is mainly affected by the Emitter mesa width and the path length between Base-Emitter electrodes, while capacitance (C) is positively correlated with pn junction width, as width is proportional to junction area. After scaling, the optimal fT values for type I and type II DHBTs are approximately 140 GHz and 450 GHz, respectively. To further optimize type I DHBT, we successfully increased fT to about 300 GHz by reducing the thickness of both the depletion layer and the base layer. Finally, we explored the differences in device characteristics between type I and type II DHBTs when the base layer thickness is reduced.