正型砷化鎵含銀多層歐姆接觸結構之研究及其應用於太陽能電池

Study of Multi-layer Silver-contained Ohmic Contact Structure on P-type GaAs and Its Application to Solar Cell

王瑞葦(Jui-Wei Wang)

指導教授 ： 廖森茂 ； 吳志宏

中原大學/工學院/電子工程研究所/碩士(2008年)

https://doi.org/10.6840/cycu200800255

摘要

本論文中將會先從探討Ni及Pt的厚度在 Ni/Pt/Ag/Au以及Ni/Ag/Au沉積在正型砷化鎵當作歐姆接觸金屬結構之影響，為了得到最低的特徵阻值，我們尋求最佳的Ni, Pt的金屬厚度還有最佳的回火條件。首先利用傳輸線模型(TLM, transmission line model)的方法求得Ni/Pt/Ag/Au金屬材料在正型砷化鎵的特徵阻值，其中發現當Ni、Pt、Ag以及Au的厚度分別是25nm、50nm、300nm及20nm時，其特徵阻值會降到最低( ρc =1.76×10-6Ω-cm2 )，回火溫度為300℃而回火時間為1分鐘。接著，利用相同方式找尋出Ni/Ag/Au金屬材料在正型砷化鎵的特徵阻值，發現當Ni、Ag以及Au的厚度分別是25nm、300nm及20nm時，其特徵阻值會降到最低( ρc=1.2×10-6Ω-cm2 )，回火溫度為300℃而回火時間為1分鐘。
　　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，經過長時間的回火(4 ~ 60小時,回火溫度為200℃)，歐姆接觸的特徵阻值的變化，我們可以發現Ni(25nm)/Ag(300nm)/Au(20nm)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，大約是增加五到十倍。
　　緊接著，將具有最低特徵阻值的歐姆接觸金屬組成結構(亦即Ni (25nm)/Ag(300nm)/ Au(20nm)) 蒸鍍在雙接面太陽能電池的正電極，來探討Ni/Ag/Au姆接觸金屬材料應用於元件上之後的元件特性，如同歐姆接觸金屬蒸鍍在正型砷化鎵基板上的結果，太陽能電池的效率(Eff)、填充因子(FF)、短路電流(Isc)、開路電壓(Voc)皆在最佳歐姆接觸金屬組成的最佳條件下有最好的表現。

關鍵字

銀 ； 歐姆接觸 ； 砷化鎵 ； 太陽能電池

並列摘要

In this dissertation, we discussed the effects of the thickness of the Ni and Pt on the Ni/Pt/Ag/Au ohmic contact metallurgical structure on p-GaAs in the beginning. We sought for the optimum thickness of the Ni and Pt layers and the suitable annealing temperature and time for the lowest specific contact resistance ρc by transmission line model method (TLM).We found out that the optimum metallurgical structure is Ni(25nm)/Pt(50nm)/Ag(300nm)/Au(20nm) which annealed at 300℃ for one minute. The lowest value (ρc=1.76×10-6 Ω-cm2) of specific contact resistance could be attained. And then, we used the same method to seek for the optimum thickness of the Ni layer and the suitable annealing temperature and time for the lowest specific contact resistance ρc. We found out that the optimum metallurgical structure is Ni(25nm)/ Ag(300nm)/Au(20nm). The lowest specific contact resistance value (ρc=1.2×10-6 Ω-cm2) could be attained. The sample annealed at 300℃ for one minute.
　　In addition, we studied the thermal stability of these ohmic contact metallurgical structures on the bulk GaAs. The ρc of these ohmic contact metallurgical structures were increased five to ten times after annealing for 4 to 60 hours when held annealing temperature at 200℃ in H2 ambient environment.
　　Sequentially, we applied the optimum ohmic contact metallurgical structure Ni (25nm) / Ag (300nm) / Au (20nm) as the positive electrode of the dual-junction (DJ) solar cells. Then, we measured the efficiency (Eff), fill factor (FF), open circuit voltage (Voc) and short circuit current (Isc) of solar cells. As the result of the optimum ohmic contact condition, all the parameters of solar cell had the best performance at the optimum ohmic contact condition.

並列關鍵字

Solar cell ； Silver ； Ohmic contact ； Gallium Arsenide

參考文獻

[9] Ken'ichi Chino and Yoshinori Wada, Jpn. J. Appl. Phys. Vol.16 (1977)pp. 1823-1828

[12] Stephen J. Pearton, Processing of wide bandgap semiconductors,2000, ISBN 0-8155-1439-5

[13] Ben G. Streetman “SOLID STATE ELECTRONIC DEVICES 4th edition” Prentice Hall Series in Solid State Physical Electronics,Nick Holonyak, Jr., Series Editor, pp.183 -189

[14] A. Y. Yu, "Electron tunneling and contact resistance of metal – silicon contact barriers," Solid-State Electron., Vol. 13, pp. 239-247,1970.

[15] C. Ting and C. Chen, "A study of the contacts of a diffused resistor," Solid-State Electron., Vol. 14. pp. 433-438, 1971.