高導電度低溫製程之氧化鎳薄膜的合成、鑑定及其結晶動力學研究

氧化鎳為一極具潛力之P型透明導電氧化物材料，經常被用於有機光電元件中作為電洞傳導層。然而，氧化鎳薄膜在製備上需要高溫且長時間的熱退火處理，導致在商業化面臨一大挑戰。因此，我們的目標即是將氧化鎳薄膜的製程溫度降低、縮短製備時間且同時能提升其電性。我們利用溶膠凝膠法製備氧化鎳薄膜，並使用四點探針、原子力顯微鏡以及低掠角X光繞射等儀器進行材料性質分析，分別求得薄膜之電性、厚度及結晶度。我們藉由共摻雜金屬離子—鋰、銅離子，來提升氧化鎳薄膜之導電度，且調控適當的摻雜比例，使氧化鎳薄膜導電度提升2倍以上，導電度由未摻雜之氧化鎳薄膜的1.90×10-3 S/cm上升至4.55×10-3 S/cm。不僅如此，我們還開發新的低溫短時間製程方法，利用添加四甲基氫氧化銨於氧化鎳前驅物溶液中作為反應物，提升氧化鎳薄膜的結晶形成速度，且由250 oC的實驗數據發現，氧化鎳薄膜之製備所需時間由原本的16分鐘降至8分鐘，且在275 oC以及300 oC的熱退火溫度下，同樣能使製程所需時間大幅減少一半。為了能更加了解氧化鎳薄膜結晶度與其物理性質之間的關係，我們以Johnson-Mehl-Avrami及Arrhenius方程式推算出氧化鎳薄膜的結晶動力學方程式，並推算得知添加四甲基氫氧化銨於前驅物溶液之氧化鎳薄膜的活化能為原本氧化鎳薄膜的二分之一，由107.81 kJ/mol降至57.91 kJ/mol，這解釋了使用四甲基氫氧化銨作為反應物能更有效率地形成氧化鎳薄膜。

關鍵字

氧化鎳薄膜；溶膠凝膠法；低溫製程；結晶動力學；導電度

並列摘要

Nickel oxide is a promising candidate for p-type transparent conducting oxide. It plays an important role in many optoelectronic devices as hole transport layer. However, the fabrication process of nickel oxide thin films inevitably requires high temperature and prolonged annealing steps, which may hinder their commercialization. Therefore, we aim to lower the fabrication temperature and shorten the fabrication time while improving their electrical properties. We prepared nickel oxide thin films by sol-gel solution process and investigated their electrical properties by four-point probe, thicknesses by atomic force microscope (AFM) and crystallinity by grazing-incidence wide-angle X-ray scattering (GIWAXS). We used the metal dopant method to enhance the conductivity of nickel oxide thin films. With appropriate amount of Li and Cu as dopants, the conductivities of nickel oxide thin films were doubled from 1.90×10-3 S/cm to 4.55×10-3 S/cm. We also demonstrated a new strategy to reduce the annealing temperature and time to save the cost of fabrication. Adding tetramethylammonium hydroxide pentahydrate (TMAOH) into nickel oxide precursors as reactant could speed up the chemical reaction and crystallization process for nickel oxide thin films. It was found that the fabrication time could be reduced from 16 min to 8 min when the annealing temperature was 250 oC. Similarly, the same trend of decreasing the processing time by half with the addition of TMAOH was also found at 275 oC and 300 oC. In order to realize the crystallization processes for two different reactions, we calculated the crystallization kinetics of nickel oxide thin films from precursors by using Johnson-Mehl-Avrami equation and Arrhenius equation. We found that with the addition of TMAOH, the activation energy of nickel oxide, 57.91 kJ/mol, was almost halved in comparison with pristine precursor, 107.81 kJ/mol. This explains the efficient formation of nickel oxide thin films using TMAOH strategy.

並列關鍵字

nickel oxide thin film ； sol-gel method ； low-temperature process ； crystallization kinetics ； conductivity

參考文獻

[33] H. Mehranpour, M. Askari, M. S. Ghamsari, H. Farzalibeik, “Study on the phase transformation kinetics of sol-gel drived TiO2 nanoparticles.” Journal of Nanomaterials, 2010, 1 (2010).

[1] J. A. Dirksen, K. Duval, T. A. Ring, “NiO thin-film formaldehyde gas sensor.” Sensors & Actuators: B. Chemical, 80, 106 (2001).

[2] S. A. El-Molla, M. N. Hammed, G. A. El-Shobaky, “Catalytic conversion of isopropanol over NiO/MgO system doped with Li2O.” Materials Letters, 58, 1003 (2004).

[3] A. ŠUrca, B. Orel, B. Pihlar, “Sol-gel derived hydrated nickel oxide electrochromic films: optical, spectroelectrochemical and structural properties.” Journal of Sol-Gel Science and Technology, 8, 743 (1997).

[4] I. M. Chan, T. Y. Hsu, F. C. Hong, “Enhanced hole injections in organic light-emitting devices by depositing nickel oxide on indium tin oxide anode.” Applied Physics Letters, 81, 1899 (2002).

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高導電度低溫製程之氧化鎳薄膜的合成、鑑定及其結晶動力學研究

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