矽與鍺在氮化鎵中的擴散行為及歐姆接點之應用

Abstract

在元件的製作及效能上,降低接點阻值是一件非常重要的事,在此之前滲雜 的方法多集中於離子佈植以及成長時同時滲雜,前者會造成不同程度的破 壞而影響元件的特性,後者則必須花費較多的時間在條件的校調上,在此論 文中我們利用一種廣為人知的方法---擴散,將滲雜與活化的處理一次解決 。實驗以不同的金屬做為擴散源,並以X繞射儀、二次離子質譜儀、複立葉 轉換紅外線光譜儀、光激光譜儀以及霍耳量測試圖瞭解其擴散行為及其現 象,研究結果顯示,在攝氏1000 oC處理後大約有43%的矽被活化,並形成n型 氮化鎵,且載子濃度為2.57x10^17cm^-3,由霍耳量測的結果可以看出移動 率且阻值隨處理溫度提昇而降低,載子濃度則隨處理溫度的昇高而提昇,在 複立葉轉換紅外線光譜圖中1800和3000 cm^-1處可以找到氮化鎵與矽的鍵 結,也同樣有隨溫度提昇強度增加的現象,另外,在光激光儀中也觀察到擴 散後產生無法確定的能階. The reduction of contact resistance is significant to fabricate device and obtain best performance. Doping method focus on the implantation and in-situ before, the former cause different damages affecting characterization ofdevice and the later cost too much time in tuning the best condition. What wehave tried in this thesis is a simple method known as diffusion to complete both doping and activation. Different metal source had been examined by XRD, SIMS, FTIR, PL and Hall measurement to explore the phenomena and analyze diffusion behaviors. Our survey displays that activation of Si up to ~43% and n-type GaN forms carrier concentration of 2.57×10^17 cm^-3. The resistivity and mobility obtained from Hall measurement present that a negative dependence on temperature opposite to carrier concentration. GaN:Si related bonds are proposed in FTIR at 1800 and 3000 cm^-1 with an increment to processing temperature. Besides, uncertainty states caused by diffusion are also observed in PL at room temperature and 20K.