量子點對硒化銅鎵光吸收係數的影響

Abstract

提升太陽能電池實際轉換效率，一直是太陽能電池研究的主要目標。本研究使用貼附靶材濺鍍靶，製備量子點硒化銅鎵光吸收層，希望藉由薄膜中的量子點產生量子侷限效應，離子化衝擊效應，歐傑再結合效應以及迷你傳送帶等機制，來提升硒化銅鎵薄膜的吸光能力。 研究使用四種材料來作為量子點，分別是硫化鉛、銻化銦、銻化鎵、硒化銅銦，並以量子點摻雜的程度、退火前後作為變因，進行XRD薄膜結晶性分析及晶粒大小，確認量子點以及薄膜的結晶結構以及結晶尺寸，Raman散射分析，鑑定摻雜量子點對薄膜結構品質的影響，使用SEM拍攝薄膜截面計算不同實驗環境下的薄膜鍍率，確保薄膜樣品厚度一致，去除因厚度造成的量測誤差，EDX用來鑑定薄膜元素組成，TEM拍攝量子點實際顆粒大小，ESCA確認薄膜中微量元素比例，UV-VI光譜儀進行光吸收係數的測量等分析，討論四種量子點材料對薄膜所造成的影響。

Improvement of photovoltaic power conversion efficiency is always the key issue in the solar cell research and development. Quantum dots, as one of the promising improvement methods, in the thin film can be applied due to the generation of impact-ionization effect, Auger recombination and miniband. In this work, co-sputtering of quantum dots on copper gallium diselenide layers via target-attach sputtering method was performed. Four various materials are utilized as our quantum dots, including PbS, InSb, GaSb and CuInSe2. This study is mainly focused on the difference of physical properties of the thin film depending on the doping of quantum dots and annealing. The instruments for characterizing the effect of quantum dots are described as follows. X-Ray Diffraction (XRD) determines the crystal quality and grain size. Raman Spectroscopy analysis detects the quality of thin film. Cross section Scanning Electron Microscope (SEM) image is applied to calculate deposition rate in the various environments to ensure the same thickness of the as-prepared films. Energy-Dispersive X-ray Spectroscopy (EDX) results characterize the element ratio of thin films. Real size of quantum dots is determined by TEM image. UV-Vis Spectroscopy analysis is conducted to compute the absorption coefficient of thin films.