氮化鎵離子佈植之特性研究

Abstract

本論文利用離子佈植的方法，針對氮化鎵薄膜進行矽與磷離子單獨或共同佈植之研究，並藉由快速熱退火處理(Rapid Thermal Anneal, RTA)，來瞭解矽、磷離子佈植對氮化鎵薄膜的影響。對於矽離子佈植之氮化鎵，經退火後，其載子濃度隨退火時間有明顯上升，特別於1100℃退火20秒，我們可得最高之矽離子活化率40%，面載子濃度亦高達2x1015 cm-2，此結果可與目前其它研究群之結果相媲美。在矽與磷共同佈植方面，我們發現磷的加入，並無法進一步提升，反而有抑制矽活化率的趨勢，這和傳統砷化鎵或磷化銦材料有著顯著不同。然而，磷的離子佈植卻能有效提升霍爾移動率，改善薄膜的電學品質，其電子移動率數值，甚至可高於未佈植之氮化鎵，由於氮化鎵的磊晶薄膜，通常具有高達108cm-2 的面缺陷濃度，磷如何降低載子運動時的散射碰撞機制，亦是未來氮化鎵研究相當有趣的研究課題。

GaN films implanted with 28Si+ and 31P+ were investigated systematically by Hall measurement and photoluminescence method. The activation efficiency of Si behaves quite differently on their implantation conditions. For Si implanted samples, a carrier concentration of 2x1015 cm-2 with ~40% activation efficiency can be obtained after a rapid thermal annealing process at 1100℃, The introduce of P ion during the Si implantation, however, bring an adverse effect on Si activation. The GaN carrier concentration was found to decrease with increase of P/Si ratio and its value is even lower than that of unimplanted ones when high concentration P is co-implanted. Such an outcome is unexpected and is rarely observed in conventional GaAs and InP materials. Nonetheless, we have found that the implantation of P+ alone can improve the Hall mobility dramatically. The reasons accounted for are still not well-understood and more investigations are needed for future study.