成果報告書詳細
管理番号20130000000132
タイトル*平成24年度中間年報 新エネルギー技術研究開発 革新的太陽光発電技術研究開発(革新型太陽電池国際研究拠点整備事業)高度秩序構造を有する薄膜多接合太陽電池の研究開発(ナロー/ワイドギャップ、高性能透明導電膜、有機単結晶)
公開日2013/10/25
報告書年度2012 - 2012
委託先名国立大学法人東京工業大学
プロジェクト番号P07015
部署名新エネルギー部
和文要約
英文要約Title: Development of epitaxial growth of single crystalline Ge and related thin films (FY2008-FY2014) FY2012 annual report

<2-1-3 Development of SiGe-based bottom cells>
The effect of SiH4 and Si2H6 in Reactive thermal CVD for hetero-epitaxial growth of Ge on Si (100) substrate was investigated, and it was found that film growth took place over 450oC, and the growth temperature was a good parameter for surface modification of Si with GeF4. In fact, in the TEM observation of the Ge film on Si substrate, the threading dislocations remained within 100nm from the Si-substrate interface. On the other hand, in Si2H6-GeF4 system, it was found that the control of the gas phase reactions for improvement of the film quality is important by suppressing the gas phase reactions. The Ge film of 600nm grown at 350oC exhibited high Hall mobility of 767cm2/Vs, and a low threading dislocation density of 7*10e5cm-2 was obtained in 1200nm thick film at the same temperature. As for the electrical properties in the films, the thermal annealing at 800oC in the presence of H2 could reduce the hole concentration down to 1016cm-3 and increase mobility from 180 cm2/Vs to 270 cm2/Vs.

<3-2-3 Development of top cell based on compound semiconductors>
In this year, we explored new n-type amorphous oxide semiconductors (AOS) which have high mobility (at least 10 cm2/Vs) and narrower band-gap energy than that of amorphous In-Ga-Zn-O (a-IGZO),because band-gap energy of a-IGZO (3.1 eV) is too large for an active layer of solar cell. Cd-M-O (M = Al, Si, Ga) films were prepared by RF magnetron sputtering method under various conditions.CdO polycrystalline films were easily obtained if films were deposited even at room temperature,however, adding another component such as Al, Si or Ga was very effective to get amorphous films.Finally, Cd-Ga-O films were discovered as a new series of n-type AOS whose band gap energy were controlled from 2.3 to 4.1 eV by varying composition. The mobilities of Eg = 2.3 eV and 4.1 eV amorphous Cd-Ga-O films were 15 and 24 cm2/Vs, respectively.

<2-2-2-1 Development of nanopatterned glass substrate and high performance TCO for organic crystal solar cells>
In this year, we investigated the large-scale nano-imprinting of the practical large glass substrates (with 2cm wide) for growth of the flat and highly crystallized ITO (indium tin oxide) thin films in order to fabricate the high performance transparent conducting oxide thin films for the organic molecule based thin film solar cell. We examined the conditions for the development of atomically ultrasmooth surfaces on commercial silicate glass substrates by the thermal nanoimprint technique using a-Al2O3 single crystal molds with 0.2 nm high atomic steps. As a result, 0.2 nm high stepped and an atomically ultrasmooth terraced surface could be formed on soda-lime silicate glass substrates with 2cm in width. The ultraflat and/or periodically stepped surface morphology of the ITO thin film reflected the atomically patterned glass substrate surface.

<2-2-2 2. Ionic liquid-assisted flux growth of organic single crystals for the organic bottom cells>
In FY2011 we have installed a digital optical microscope with a long-distance focal lens to directly monitor the growth behavior of organic crystals in ionic liquid, and thereby have achieved a better reproducibility in the fabrication process.
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