成果報告書詳細
管理番号20120000000544
タイトル*平成23年度中間年報 太陽エネルギー技術研究開発 太陽光発電システム次世代高性能技術の開発 極限シリコン結晶太陽電池の研究開発(浮遊キャスト成長法による高品質Si多結晶インゴット結晶成長技術)
公開日2012/12/26
報告書年度2011-2011
委託先名国立大学法人京都大学
プロジェクト番号P07015
部署名新エネルギー部
和文要約和文要約等以下本編抜粋:
[記載項目]
1.研究開発の内容及び成果等
今年度の成果のポイントを以下に記す。
平成23年度は主として以下の成果を得た。
浮遊キャスト成長法によるインゴットの高品質化のための成長技術の基礎検討(京都大学)
1)本技術は、Si融液表面からSi種結晶を用いて結晶成長を開始し、融液内部に設けた低温領域内でインゴット結晶を成長させ、その後低温領域内での成長を確保しつつインゴットを引き上げ、ルツボの壁に触れない歪みの少ない高品質Si多結晶インゴットを得る方法である(図1)。
英文要約Title: High Performance PV Generation System for the Future. R and D on Ultimate Wafer-based Si Solar Cells. (Growth technology of high-quality Si multicrystal ingots using the Floating Cast Method), (FY2010-FY2012) FY2011 Annual Report
Basic research for the growth technology to obtain high-quality Si multicrystal ingots using "the Floating Cast Method" (Kyoto University). “The Floating Cast Method” is a method for obtaining a high-quality Si multicrystal ingot with low stress. In this method, the Si melt has a low-temperature region in its central upper part. The crystal grows naturally in the low-temperature region without touching wall of a crucible, then it is slowly pulled upward while ensuring that crystal growth remains in the low-temperature region. Because the growing crystal does not touch the crucible wall, this technology has a potential to obtain high-quality ingot without impurity contamination, multi-crystallization and generation of defects and strain from the crucible wall. In this research period (FY2011), we have demonstrated that crystal growth is able to be done within Si melt by this growth method. We succeeded in growing an ingot by this method in which most of grain boundaries are electrically inactive twin boundaries in the region with large grain unaffected by Si3N4 coating. This ensures that ideal Si multicrystal ingot consisting only of several grain boundaries and twin boundaries can be obtained if the influence of Si3N4 carting can be suppressed. This study bases on growth of crystal ingot without touching crucible wall. In order to realize this growth, this method is characterized by forming a low-temperature region in the Si melt. By controlling the size of this low-temperature region, we succeeded in controlling the mass of crystals and the diameter of crystal ingots. Si multicrystal ingots of large volume (7100-9260 g) and large diameter (23-26 cm) were achieved in spite of small size (diameter 25-33 cm) of a crucible. Maximum and average carrier diffusion length of 610 and 173 micro-meters were obtained from a sample of ingot side. In addition, a large wafer that is slightly smaller than 15.6 x 15.6 cm showed average carrier lifetime of 25 micro-sec. The oxygen concentration in the crystal was approximately one order of magnitude lower than that in a monocrystallie Si grown by Czochralski (CZ) method owing to Si3N4 carting on the crucible wall, as well as the oxygen concentration in the crystals grown by casting method. As the result of FTIR measurements, the oxygen concentration in the crystals grown by this method was 0.5-1.6 x 1017/cm2. For comparison, typical oxygen concentrations are 1-8 x 1017/cm2 in crystals grown by casting method and 1 x 1018/cm2 in the crystals grown by CZ method. For the next fiscal year, we shift emphasis to solve the problems of degradation of the ingot quality by contamination from vapor-phase, multi-crystallization caused by Si3N4 carting and introduction of dislocation due to thermal shock.
ダウンロード成果報告書データベース(ユーザ登録必須)から、ダウンロードしてください。

▲トップに戻る