正型砷化鎵含銅多層歐姆接觸結構 之研究及其應用

Study of multi-layer copper-contained ohmic contact structure on p-type GaAs and its application

林致遠(Chih-Yuan Lin)

指導教授 ： 廖森茂

中原大學/工學院/電子工程研究所/碩士(2007年)

https://doi.org/10.6840/cycu200700223

摘要

本論文中將會先從探討Cu的厚度在 Ni/Pt/Cu/Au 以及Ni , Pt及Cu的厚度對於 Ni/Pt/Cu/Ni/Au 沉積在正型砷化鎵當作歐姆接觸之影響，為了得到最低的特徵阻值，我們尋求最佳的Ni, Pt及Cu的金屬厚度還有最佳的回火條件。首先利用TLM (transmission line model)的方法求得Ni/Pt/Cu/Ni/Au金屬材料在正型砷化鎵的特徵阻值，其中發現當Ni, Pt及Cu的厚度分別由20nm, 20nm及20nm增加到50nm, 50nm及160nm時，其特徵阻值會降到最低 ( ρc 2.22×10-6 Ω-cm2 )，回火溫度為280℃而回火時間為1分鐘。緊接著，將具有最低特徵阻值的歐姆接觸金屬組成(亦即Ni (50nm)/ Pt (50nm)/ Cu (160nm)/ Ni (40nm)/ Au (50nm))蒸鍍在雙接面太陽能電池的正電極，並且與未含Cu的歐姆接觸金屬組成(亦即Ni (50nm)/ Pt (80nm)/ Au(200nm))做比較，來探討Ni/Pt/Cu/Ni/Au材料應用於元件上之後的元件特性。
此外，我們也研究此歐姆接觸金屬蒸鍍在正型砷化鎵基板上及雙接面太陽能電池上，經過長時間的回火(0分鐘 到 12小時)，歐姆接觸的特徵阻值及效率的變化，我們可以發現Ni (50nm)/ Pt (50nm)/ Cu (160nm)/ Ni (40nm)/ Au (50nm) 這個冶金結構在正型砷化鎵上，特徵阻值會隨著回火時間的增加而增加，而此冶金結構在太陽能電池上當作正電極時，發電的效率也會隨著回火時間的增加而降低。

關鍵字

太陽能電池 ； 熱穩定 ； 歐姆接觸 ； 銅

並列摘要

In this dissertation, we discussed the effects of the thickness of the Cu on the Ni/Pt/Cu/Au contact and of the individual Ni, Pt and Cu on the Ni/Pt/Cu/Ni/Au contact to p-GaAs in the beginning. Then, we sought for the optimum thickness of the Ni, Pt and Cu layers and the suitable annealing temperature and time for the lowest specific contact resistance ρc by transmission line method (TLM). As increasing the thickness of the Ni, Pt and Cu layers to 50nm, 50nm and 160nm, respectively, the lowest value (ρc 2.22×10-6 Ω-cm2) of specific contact resistance could be attained.
Sequentially, we applied the optimum metallurgical structure of Ni (50nm) / Pt (50nm) / Cu (160nm) / Ni (40nm) / Au (50nm) layers as the positive electrode of the dual-junction (DJ) solar cells. Then, we measured these solar cells efficiency and compared the results with those of DJ solar cells having Ni (50nm) / Pt (80nm) / Au (200nm) p-type ohmic contact but without the copper metallurgical structure. We obtained the conversion efficiency about 17.19% for DJ solar cell with Ni (50nm) / Pt (50nm) / Cu (160nm) / Ni (40nm) / Au (50nm) and 17.39% for that with Ni (50nm) / Pt (80nm) / Au (200nm).
In addition, we studied the thermal stability of these contact metals on the bulk GaAs and DJ solar cells. The ρc of Ni (50nm)/Pt (50nm)/Cu (160nm)/Ni (40nm)/Au (50nm) metallurgical structure is increased from 2.22×10-6 Ω-cm2 to 2.26×10-5 Ω-cm2 and the efficiency of DJ solar cell is decreased from 17.19% to 15.89% after annealing for 12 hours when held annealing temperature at 200oC in H2 ambient environment.

並列關鍵字

copper ； thermal stability ； ohmic contact ； solar cell

參考文獻

Referances

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