近年來矽薄膜太陽電池逐漸受到重視是由於矽單晶太陽電池消耗許多矽材料。目前最成熟的矽薄膜太陽電池結構是非晶矽(a-Si:H)及微晶系(μc-Si:H)所堆疊的串疊型電池(tandem cells)。多晶矽薄膜給予了另一個探索方向。鋁誘發結晶Aluminum induced crystallization (AIC)是另一種可期待的多晶矽薄膜製程技術，其熱處理溫度相對較低(~400℃)且時間也可接受。
IMEC發展的AIC薄膜太陽電池可以達到8%。而更高的效率難以達到其中一個原因在於矽薄膜晶粒中缺陷(intragrain defect)，此缺陷是AIC本身的特質。所以除了消除晶粒中缺陷，從結構改良來提高電池效率也是一方法。我們研究將下電極從點電極型式改良成全面下電極，如此除了可以降低金屬電極與矽的接觸電阻也可提高單一電池的吸光面積進而提高電池效率。全面下電極利用的材料之一鎳鋁合金( NiAl )有低電阻率 (~1E-5Ωcm) 及可承受後續磊晶製程的高溫(1638℃) 。此外，鎳鋁合金並不與矽反應形成矽化鎳乃由於逆反應是較易發生的。
本論文利用射頻濺鍍將AIC與Ni/Al多層膜堆疊並同時熱處理進行反應，達到將晶種層多晶矽薄膜與下電極NiAl堆疊的目的，其中多晶矽薄膜約100nm，NiAl約500nm。利用X光繞射(XRD,X-ray diffraction)分析其鎳鋁合金的相，以及穿透式電子顯微鏡(TEM, transmission electron microscope)分析薄膜之顯微結構。利用轉換長度模型(TLM, transfer length model)量測多晶矽與鎳鋁合金之接觸電阻，並利用電流-電壓特性曲線(I-V characteristics)確認其為歐姆接觸。
多晶矽薄膜晶粒尺寸約700nm，具體接觸電阻率可達到小於1mΩ∙cm^2。

Thin film Si solar cells on inexpensive foreign substrates have attracted much attention in recent years because bulk Si based solar cells consume a lot of Si wafers which is the main contribution of high cost in the technology. The most mature Si thin film solar cells are the structures based on amorphous Si (a-Si:H) and microcrystalline Si (μc-Si:H). Aluminum induced crystallization (AIC) is one of another promising technology for fabricating pc-Si since its heat treatment temperature is comparably low (~400℃) and duration is fair.
Solar cells based on AIC technology have reached the highest efficiency of 8% demonstrated by IMEC. Higher efficiency is difficult to reach due to the presence of intragrain defects which is an intrinsic defect of AIC. Altering cell structures may be one of the solutions to reach higher efficiency. In this thesis, we study the fabrication of high temperature back contact on full back area of cells rather than point contact to increase efficiency by lowering contact resistance between semiconductor and electrode. Our approach also increases area for incident light per unit cell. Nickel aluminide( NiAl ) is one of the candidates because of its low resistivity (~1E-5Ωcm) and high melting point (1638℃) which can sustain high temperature of epitaxy process for Si thickening. On the other hand, nickel aluminide do not react with pc-Si to form nickel silicide since Ni-Al bonding is more preffered than Ni-Si bonding.
In this thesis， AIC and Ni/Al multilayer structures was deposited by RF-sputtering process then is annealed to proceed chemical reaction in order to form seed layer, pc-Si film and bottom electrode, NiAl, which has 100nm and 500nm in thickness, respectively. XRD was using for phase indenfication for NiAl. Microstructure of the films were explored by TEM. TLM (transfer length model) was applied to measure contact resistance, and junction characters were checked by I-V characteristics.
The grain size of pc-Si film can achieve about 700nm, and the specific contact resistivity can be lower than 1mΩ∙cm^2.

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