- 學位論文
不同鍍材密度對電子束蒸鍍氧化銦錫薄膜特性之研究
Investigation of ITO Thin Film Characteristics Using Electron Beam Evaporation with Different Source Densities.
摘要
中文摘要 近來，透明金屬氧化物在光電產業上的應用越來越為廣泛，尤其是在發光二極體-氮化鎵的電極材料方面，傳統的電極接觸材料常使用高功函數的金屬，如: 鎳、金、鈦等材料來跟P-型的氮化鎵形成歐姆接觸，以利載子的注入。然而由於P-型氮化鎵的內部載子濃度較低因此發光效率差，若再被上層金屬遮光後，則整體亮度下降許多，因此近年來越來越多的研究團隊利用透明導電金屬氧化物來製作氮化鎵的上層電極。目前製作透明金屬氧化物的方法不外乎是利用濺鍍或是電子束蒸鍍的方法來進行，但是在濺鍍的過程中所產生的高能量電漿將會對元件接面造成物理的撞擊傷害進而影響元件特性。因此，在量產上製作氮化鎵的透明電極時，就以電子束蒸鍍為主。而在電子束的蒸鍍源方面，所使用的ITO鍍材又可區分為高密度材料及低密度材料。本研究論文在沈積條件固定不變下，不管是使用高或低密度的ITO鍍材，蒸鍍所獲得之鍍膜鎖其光電特性均非常類似，片電阻值約在7.5~8.5 ohm/sq，而穿透度在可見光範圍內約在85%~95%之間，然而應用在LED元件製程中，低密度的鍍材就表現出不穩定性，也就是薄膜電阻值有增大的現象，其電阻值略高於高密度ITO鍍材。利用低密度鍍材所製作的LED元件，其啟動電壓比高密度者約大0.1V。 本篇論文探討不同密度的ITO鍍材所獲得的薄膜特性，並提供一個適當的技術來作為日後設計電子束蒸鍍機時的重要參考依據。
關鍵字
無資料並列摘要
Abstract Recently, transparent metal oxide is widely used in optoelectronics, especially in the application of electrode for GaN LEDs. The conventional electrode material is usually high work function metal such as Ni, Au, and Ti, in order to achieve the ohmic contact with the p-type GaN. However, the low carrier concentration of p-type GaN will lead to the low emitting efficiency. Moreover, if the opaque metals shelter the emitting light that will cause the lower and lower efficiency. Therefore, there is more and more group using transparent conductive oxide TCO material as the transparent electrode to improve the quantum efficiency, especially ITO material. Generally, ITO will be deposited by sputtering or E-beam evaporation. But, to consider that the sputtering process will bring out bombard damage to the surface that will degrade the performance of device. The E-beam evaporation seems to be a better choice. The ITO deposition source can divide into high density and low density. In this work, we will discuss the influence of different density for ITO source. The ITO source can separate into the high density and the low density source. Base on the investigation of this thesis, under the identical deposition condition, the influence for the characteristic is not apparent. The sheet resistance is about 7.5~8.5 ohm/sq, and the transparency in the visible region is from 85% to 95%. However, for the LED application, the ITO film of low density material will show the non-stability, corresponding to the increasing of resistivity. The operation voltage is increased about 0.1 V.Moreover, we want to provide a method for the reference to design the equipment of E-beam evaporation.