磷化銦鎵異質接面電晶體及高速電子遷移率電晶體之研究

Abstract

本篇論文主要是針對磷化銦鎵異質接面電晶體及高速電子遷移率電晶體之研究。在這本論文□，我們主要分為兩大部份來討論。第一部份是磷化銦鎵異質接面電晶體元件的研究。第二部份是磷化銦鎵高速電子遷移率電晶體元件的研究。 在論文的第一部份，我們描述了異質接面電晶體的半導體製作流程。接著我們改變異質接面電晶體中射極到基極的距離，研究這距離的變化對磷化銦鎵異質接面電晶體所產生的電性變化。在這論文的研究中，我們將射極到基極的距離從0.2 μm 到 2μm的變化，試圖找出最佳的射極到基極距離。從實驗的資料顯示，對於磷化銦鎵異質接面電晶體的功率放大器應用而言，0.6 μm 到 0.8μm的距離是最佳的距離。在這最佳的射極到基極的距離□，磷化銦鎵異質接面電晶體元件可以同時得到好的直流及高頻特性。稍後在這論文□，我們將會對這特性再做更詳細的討論。 在磷化銦鎵異質接面電晶體的元件電路應用上,元件電性模型的建立也是一個重要的工作。在這個部份中,我們描述了元件電性模型的建立理論及參數箤取方法。並且我們也利用所製作出來的異質接面電晶體的量測特性和我們的元件電性模型的模擬結果來比較。 在論文的第二部份，我們主要研究了磷化銦鎵/砷化銦鎵/砷化鋁鎵及磷化銦鎵/砷化銦鎵/砷化鎵的高速電子遷移率電晶體。在這個部份中，我們首先針對元件的製作流程予以解說。在這論文□，我們都是使用磷化銦鎵當作我們的閘極位障層，我們利用它來侷限通道電子。而且磷化銦鎵的材料沒有著砷化鋁鎵的材料的缺點，那就是深態位阱。在我們所研究的這兩種結構的高速電子遷移電晶體，均可得到良好的元件特性。當我們將閘極的通道長度降到0.3μm時，我們在這二種元件結構上都沒有發現到有元件短通道的效應發生。從實驗的資料顯示，磷化銦鎵/砷化銦鎵/砷化鋁鎵高速電子遷移率電晶體有著比磷化銦鎵/砷化銦鎵/砷化鎵高速電子遷移率電晶體更好的元件特性，如較高的轉換電導係數、較高的電流驅動能力、和較好的高頻及雜訊表現。所有的這些優點主要是來自於磷化銦鎵/砷化銦鎵/砷化鋁鎵高速電子遷移率電晶體有著比較好電流侷限位障。因此由這結果我們知道磷化銦鎵/砷化銦鎵/砷化鋁鎵高速電子遷移率電晶體在微波的應用可以得到良好的特性。

The InGaP Heterojunction Bipolar Transistor (HBT) and Pseudomorphic High Electron Mobility Transistor (PHEMT) are investigated in this dissertation. The discussions of these two type transistors are divided in two parts. Part I is the HBT device and Part II is the PHEMT device. In the Part I, the discussion involves fabrication process of the HBT. After the process flow discussion, the study continued with the influence of varying the spacing between emitter and base in InGaP HBTs. In the discussion, an initial spacing was set, and then the spacing was varied until the critical spacing was established between emitter and base in power InGaP HBT’s. The emitter to base spacing could be as small as 0.6um and causes little drop in gain. From experimental data, emitter-to-base spacing reduction leads to improvement in high-frequency performance. For optimal dc and rf performances, a critical spacing of 0.6 ~ 0.8um between emitter and base of power InGaP HBT’s has been verified. A more in depth discussion in the HBT device modeling is work out in the thesis. In the part II, the PHEMT process flow is described and the verifications were carried out for DC, RF, and noise characteristics of InGaP/InGaAs/AlGaAs and InGaP/InGaAs/GaAs PHEMTs. The InGaP gate barrier was studied because it provides adequate carrier confinement for the channel carriers. At the same time, it also eliminates the problems associated with AlGaAs. Excellent device performance was obtained for both types of devices. During the study, the short channel effect was not observed until the gate length was in the scale of 0.3mm. The InGaP/InGaAs/AlGaAs PHEMTs surpass the InGaP/InGaAs/GaAs one with a higher transconductance, higher current carrying capability and a better RF performance. All these were attributed to the enhanced carrier confinement at the back channel. The results have demonstrated that InGaP/InGaAs/AlGaAs PHEMTs are superior candidates for the microwave applications.