태양전지용 다결정 규소 박판의 제조-캐스팅 변수들에 따른 규소 박판의 물성 변화-

소원욱; 윤경구; 김희영; 문상진

HWAHAK KONGHAK, Vol.29, No.5, 534-544, October, 1991

Manufacturing of Solar-grade Polycrystalline Silicon Wafer-Variation of Physical Properties of Silicon Wafer with the Casting Variables-

소원욱, 윤경구, 김희영, 문상진

초록

캐스팅법에 의한 태양전지용 다결정 규소 박판의 제조시, 도가니 냉각속도, 도가니 회전/이동, 도가니 두께, 피복물질, 원료규소의 종류 변화와 같은 주요 캐스팅 변수들에 대한 영향을 고찰하였다. 냉각속도는 1℃/min 근방에서 낮을수록, 도가니는 회전(1.5rpm)과 동시에 하부 이동(3.5cm/hr)시켜 온도구배를 키울수록 양질의 주상결정구조를 얻을 수 있었다. 또한 CaCl₂ 나 Si₃N₄와 같은 피복물질의 종류, off-grade 규소와 같은 원료규소의 종류에 상관없이 허용 불순물 농도는 모두 한계치 이하 값을 나타내었다. 주어진 변수들의 적절한 범위 안에서 본 캐스팅법의 방향성 응고에 의한 편석현상과 주상구조의 결정성장으로, 고효율 태양전지용 다결정 규소 막판을 제조하는 것이 기술적으로 용이하였다.

Effects of major casting variables such as the crucible cooling rate, rotation/translation of the crucible, wall thickness of the crucible, the coating material, and the class of feed sillicon on the electro-physical properties of solar-grade polycrystalline silicon wafers were examined. The crystalline structures showed better colummar structures as the cooling rate was gradually reduced around the level of 1℃/min, and as proper rotation(1.5rpm)and translation(3.5cm/hr) of the crucible were performed at the same time. Impurity concentrations of cast wafers were on much lower levels than the limit values allowed for the high efficiency(i.e. above 10%) solar cells, irrespective of the kinds of feed silicons and coating materials. Within the proper ranges of above casting variables, it was feasible technically to manufacture the polycrystal-line silicon wafers for the high efficiency solar cells using the impurity segregation effect and growth of the columar structure due to the directional solidification phenomena of the present casting method.

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[1] So WW, Yoon KK, Moon SJ, Yoon P, HWAHAK KONGHAK, 27(6), 823 (1989)

[2] Moon SJ, So WW, Yoon P, HWAHAK KONGHAK, 27(5), 689 (1989)

[3] Brice JC, "The Growth of Crystals from Liquids," North Holland Publishing Co., Amsterdam (1973)

[4] Hyland S, Iles P, Leung D, Schwuttke GH, Engelbrecht JAA, Proc. 16th IEEE Photovoltaic Specialists Conf., 68 (1982)

[5] Daud T, Dumas KA, Schwuttke GH, Smetana P, Kim KM, Proc. 16th IEEE Photovoltaic Specialists Conf., 63 (1982)

[6] Ravishankar PS, Dismukes JP, J. Cryst. Growth, 71, 579 (1985)

[7] Ravishankar PS, J. Cryst. Growth, 94, 62 (1989)

[8] ASTM Standards: F121-83, 234 (1984)

[9] Fally J, Guignot C, Goeffon L, Proc. 7th E.C. Photovoltaic Solar Energy Conf., 961 (1985)

[10] Gasparini M, Calligarich C, Rava P, Sardi L, Alessandri L, Redaelli F, Pizzini S, Proc. 16th IEEE Photovoltaic Specialists Conf., 74 (1982)

[11] Cullk JS, Proc. 18th IEEe Photovoltaic Specialists Conf., 1170 (1984)

[12] Saito T, Shimura A, Ichikawa S, Proc. 15th IEEE Photovoltaic Specialists Conf., 576 (1981)