佈植鐵離子之CuInSe2薄膜的晶體結構、磁性及光學能帶研究

The Study of Crystal Structure, Magnetic Property and Optical Band Structure of Fe Implanted CuInSe2 Thin Films.

劉禮榮(Li-Jung Liu)

指導教授 ： 李志浩

國立清華大學/原子科學院/工程與系統科學系/碩士(2007年)

https://doi.org/10.6843/NTHU.2007.00586

摘要

摘要

本實驗利用離子佈植的方式，佈植鐵離子於CuInSe2薄膜中，嘗試將CuInSe2薄膜改質為具有鐵磁性與中間能帶的半導體材料。
從X光繞射以及X光吸收光譜所得到的結果可知，在最高佈值劑量下，佈植之鐵原子以純鐵相存在於CuInSe2薄膜中，並且具有鐵磁性，經場冷及零場冷量測後發現，其居禮溫度大於300 K，但磁特性應是來自於薄膜中的鐵顆粒。於低佈植劑量下，經過磁特性量測後發現，亦具有室溫鐵磁性，而且鐵原子是以+2價的狀態存在；不同佈植劑量下，其磁特性之變化與造成光學特性變化之自由載子濃度變化趨勢相似；因此我們猜測，低劑量之樣品磁特性來源，可能是源自載子誘發之本質稀磁性半導體的表現。
在高佈植濃度下所出現的能隙中間的吸收峰，低佈植劑量下卻沒有被觀察到；可能是因為在低佈植劑量下，雜質原子的數量並不足以讓原本的CuInSe2薄膜產生新的中間能帶吸收峰。
因此，如何有效的在低佈植劑量下產生新的吸收能帶，將會是未來發展的重要課題。

關鍵字

太陽能電池 ； 銅銦硒 ； 離子佈植 ； 鐵 ； 稀磁性半導體 ； 中間能帶材料

並列摘要

Abstract
An iron implanted CuInSe2 semiconductor thin film to process a ferromagnetic property and intermediate band structure by utilizing the ion implantation technique was studied in this work.
From the measurements of the X-ray diffraction and the X-ray absorption spectra, the status of the implanted iron atoms in high dose implanted CuInSe2 thin films was similar to the pure iron bulk, and the ferromagnetic property was observed. Base on the results of the measurements of zero-field cooled and field cooled, the Curie temperature was above the room temperature (300 K), but the ferromagnetic property might come from the iron clusters in the films. At light dose of the CuInSe2 thin films, the room temperature ferromagnetic property was still exist, and the valence state of the implanted iron atoms was +2. The variation of the magnetic property at different doses was similar to the variations of concentration of the excess free carriers which cause also the optical band shifts. So, we consider that the magnetic property of the light dose implanted thin films should come from the intrinsic carrier mediated property.
The additional absorption at the middle of the band gap energy was only observed at the high dose implanted thin films. We think that the concentration of the light dose implanted thin film isn’t high enough to create a new absorption band at the middle of band gap.
How to create a new absorption band at the middle of band gap at light dose implanted thin films will be a very important subject for the future development.

並列關鍵字

solar cell ； CuInSe2 ； Ion implantation ； iron ； Diluted Magnetic Semiconductor ； Intermediate band material

參考文獻

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