| DC 欄位 |
值 |
語言 |
| DC.contributor | 材料科學與工程研究所 | zh_TW |
| DC.creator | 陳昱達 | zh_TW |
| DC.creator | Yuh-dar Chen | en_US |
| dc.date.accessioned | 2010-8-9T07:39:07Z | |
| dc.date.available | 2010-8-9T07:39:07Z | |
| dc.date.issued | 2010 | |
| dc.identifier.uri | http://ir.lib.ncu.edu.tw:88/thesis/view_etd.asp?URN=973209002 | |
| dc.contributor.department | 材料科學與工程研究所 | zh_TW |
| DC.description | 國立中央大學 | zh_TW |
| DC.description | National Central University | en_US |
| dc.description.abstract | 隨著GaN-based 發光二極體的蓬勃發展，為了達到固態照明的目標，主要從元件頂部透明導電層發光的傳統LED已無法滿足此需求，因此目前有垂直結構LED和覆晶結構LED這兩種類型的元件結構被提出來製作超高亮度LED，對於這兩種類型LED，尋求一個具有高度反射性且與p型氮化鎵有低接觸電阻的歐姆接觸結構是關鍵的，其中銀因為在可見光範圍中有最高的反射性以及能夠經由退火和p型氮化鎵形成良好的歐姆接觸，所以是相當不錯的選擇，但是當它在快速熱退火處理來獲得低的接觸電阻或者在和其他基板作鍵合時，銀薄膜會因為快速地發生聚集的現象，造成薄膜瓦解成許多島狀物而露出氮化鎵表面，這會使得接觸電阻增加和反射性降低，造成元件驅動電壓增加與光輸出功率減少，所以讓銀維持良好的薄膜狀態是很重要的，有鑑於此，我們在銀薄膜上，多鍍上一層薄的鑭層，此種接觸結構在450℃快速熱退火後，會具有比銀接觸結構更低的特徵接觸電阻以及更高的反射率分別為3.449×10-4Ω cm2和96％，它能具備如此優良的表現是因為鑭本身非常容易氧化，而氧化鑭在退火時，能夠做為一良好的鈍化層，防止銀薄膜曝露在含有氧氣的環境中，所以可以避免因為銀原子表面擴散係數的大幅增加而造成的嚴重聚集，此外我們也藉由長時間退火來測試Ag/La結構之熱穩定度，以了解其在高功率發光二極體元件的鍵合製程時之可靠度，實驗結果顯示此結構在長時間熱處理後，仍然具有良好的性質，因此銀鑭雙層結構十分適合當作p型氮化鎵的反射性歐姆接觸。
| zh_TW |
| dc.description.abstract | GaN-based Light-emitting diode has great progress in recent years. In order to achieve the purpose of solid-state lighting, conventional LED which emit most light through the transparent conducting layer on the top of device could not satisfy this demand. Two types of LED device structure, which are vertical structure LED and flip-chip structure LED, have been proposed to fabricate high brightness LED. For these LEDs, it is critical to search for a ohmic contact structure which is highly reflective and low contact resistance to p-GaN. In all materials, silver is a good choice for being used as a p-GaN ohmic contact because it has the highest reflectivity in visible spectrum and forms a good contact to p-GaN by annealing. But Ag film would agglomerate rapidly and be divided into lots of islands when it was rapid-thermal-annealed for obtaining low contact resistance or bonded with another substrate. The phenomena described above resulted in the increase of forward voltage of device and the decrease of light output power. So it is important to avoid the agglomeration of silver thin film. For this reason, we evaporated a thin lanthanum layer on thick Ag layer. After rapid-thermal-annealing at 450℃for 1minute, this structure exhibited the lower specific contact resistivity of 3.449×10-4Ω cm2 and higher reflectivity of 96％ than single Ag contact. The reason why it has better performance is that lanthanum is easy to oxidize into lanthanum oxide. And it may be a good passivation layer for preventing Ag film from exposing in oxygen-containing ambience. As a result, it could inhibit the serious agglomeration of Ag film which was caused by the drastic increase of surface diffusion coefficient of Ag atom. Besides, we tested the thermal stability of Ag/La bilayer structure for investigating the reliability of this structure during the bonding process of two LEDs. Experimental results showed that it still had the good property after long-time heat treatment. Therefore, Ag (200nm) / La (40nm) bilayer structure is suitable for the reflective ohmic contact of p-GaN.
| en_US |
| DC.subject | 歐姆接觸 | zh_TW |
| DC.subject | 氮化鎵 | zh_TW |
| DC.subject | ohmic contact | en_US |
| DC.subject | gallium nitride | en_US |
| DC.title | 高度反射性銀/鑭雙層p型氮化鎵歐姆接觸之性質研究 | zh_TW |
| dc.language.iso | zh-TW | zh-TW |
| DC.title | Highly reflective Ag/La bilayer ohmic contacts on p-GaN | en_US |
| DC.type | 博碩士論文 | zh_TW |
| DC.type | thesis | en_US |
| DC.publisher | National Central University | en_US |