N型太陽能多晶矽的晶向控制及去疵之研究

Grain Control and Gettering of N-type Multi-Crystalline Silicon for Photovoltaic Applications

黃皓堅(Hao-Chien Huang)

指導教授 ： 藍崇文

國立臺灣大學/工學院/化學工程學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.10015

摘要

N型結晶矽相較於P型結晶矽有較高的少數載子壽命，且對於常見的金屬雜質的容忍度較高，在此論文當中吾人將生長N型多晶矽並將其電阻控制在0.5到1.5 Ω-cm之間，並同時使用spot cooling控制晶向和側向保溫改善界面，使有控制之N型多晶矽的晶粒隨著晶碇生長的高度增加而放大。從EBSD的分析觀察控制晶體之晶向分佈，吾人發現在有控制之晶體的頂部晶片，觀察到有大量的{112}方向的晶粒生成，而少數載子壽命也是隨著晶粒放大而有增加的趨勢。並使用Seco液蝕刻出晶片的缺陷，再由金相顯微鏡觀察其EPD的分佈以及對照其PL的影像，發現其中有晶向控制之晶體的缺陷密度隨著生長高度增加而有遞減的趨勢，且在控制晶體的頂部晶片最低可達103 cm-2，最後對有控制的晶片加入外部去疵的程序，使其少數載子壽命能夠再提升。

關鍵字

N型多晶矽 ； 晶向控制 ； 外部去疵

並列摘要

N-type silicon solar cell has attracted notice recently because of its high endurance to common impurity and higher minority carrier lifetime than p-type silicon. We have grown n-type mc-silicon crystal and control the resistivity distribution from 0.5 to 1.5 (Ω-cm). The active cooling spot was implemented at crucible bottom to control the grains and side insulation to enhance the grain size in n-type mc-silicon during directional solidification. The EBSD mapping of controlled ingot was measured to investigate the effect on active cooling spot, we also find out the grain orientation in the top of ingot was {112} dominant, and the minority carrier lifetime increased with the height of ingot. The wafers were also etched with a Seco solution to detect crystallographic defects by metallographic microscope and Photoluminescence images. The etch-pits density at the top wafer of controlled ingot had the lowest value about 103 cm-2. Finally, we used the phosphorus gettering to remove impurity from the wafers of controlled ingot, and its enhanced the lifetime of the controlled wafer.

並列關鍵字

n-type multi-crystalline silicon ； grain control ； external gettering

參考文獻

[1] M.A. Green, K. Emery, Y. Hishikawa, W. Warta, Solar cell efficiency tables (version 37), Prog Photovoltaics, 19 (2011) 84-92.

[5] 費致傑, 熱退火對太陽能多晶矽影響之研究, (2010) 50.

[6] K. Bothe, R. Sinton, J. Schmidt, Fundamental boron-oxygen-related carrier lifetime limit in mono- and multicrystalline silicon, Prog Photovoltaics, 13 (2005) 287-296.

[7] K.D. Smith, R.J. Nielsen, H.K. Gummel, D.B. Cuttriss, W. Rosenzweig, J.D. Bode, Solar Cells and Their Mounting, Bell Syst Tech J, 42 (1963) 1765-+.

[8] T. Schulz-Kuchly, Light-Induced-Degradation effects in boron–phosphorus compensated