金屬催化物於砷化銦奈米線成長與奈米結構化銦參雜氧化錫基板製作高效能電子元件之影響

Catalytic Effect on InAs Nanowire Growth and Nanostructured ITO Substrate for High Performance Electron Devices

陳思穎(SZU-YING CHEN)

指導教授 ： 陳力俊 ； 闕郁倫

國立清華大學/工學院/材料科學工程學系/博士(2013年)

https://doi.org/10.6843/NTHU.2013.00122

摘要

本研究中主要分為兩個部分,第一部分為金屬催化劑對於砷 化銦奈米線成長的影響,並利用接觸印刷的技術製作大尺寸奈米線陣 列於高效能電晶體特性之應用。另一部分則為延續大規模陣列奈米結 構之影響,探討奈米碗結構之銦參雜氧化錫基板於有機太陽能電池之 高效能元件應用。
第一部分中,主要探討金屬催化劑在砷化銦奈米線成長之影 響。利用,臨場高溫 x 光繞射分析晶體,觀察在高溫中,金屬催化劑 與砷化銦行為,並利用臨場穿透式電子顯微鏡觀察在高溫中,不同金 屬催化物具有不同偏析的行為。推測其化學當量比的差異主要之貢獻, 並推測其可能的成長機制。
另一方面,延續不同催化劑所成長之砷化銦奈米線於薄膜電晶 體元件應用上,發現僅有~20 % 對於背電極控制有較強的相關性, ~80 %為較不易被被電極所控制。反之,利用鎳催化成長之砷化銦奈 米線,約有~98 % 具有良好的 n-type 半導體特性。在鎳催化之奈米 線元件中,關閉電流(off-current)約為 ~10-10 A,且具有良好的電流開 關(ION/IOFF ratio)比約大於 104。以金為催化劑成長之砷化銦奈米線, 具有較不穩定的墊子傳輸特性,推測原因可能來自於此種奈米線偏離了化學當量比。由於利用不同催化劑具有不同的電子傳輸行為,在此研究中更進一步的利用第一原理計算證明。同時製作了上背電極元件 以及利用接觸印刷的技術製作大面積高效能元件。
第二部研究中,延續著奈米陣列於元件的應用,主要著重於 大規模二維奈米碗陣列結構於有機太陽能電池的應用。此研究中,利 用 Langmuir–Blodgett (LB)薄膜製備方法,將聚苯乙烯奈米球陣列排 列於基板上。利用控制不同的尺寸的奈米球,我們可控制二維奈米陣 列表面形貌。利用此奈米結構化的銦參雜氧化錫基板,製作有機太陽 能電池。研究中發現,此結構化的機板可將反射率降至~20 %, 與未 結構化的基板比較,可成功的降低 5–7 % 反射率。此種建立於奈米 結構化基板的有機太陽能電池,具有最高的太陽能轉換效率約為 5.4 %,填充因子約為 66 %,比起平面基板所製作的有機太陽能電池, 效率最高效率 3.9 %,可有效的提升太陽能轉換效率約為~40 % 。由 於結構化後的銦參雜氧化錫基板,有效的降低反射,增加光在有機層 中行走路徑,因此有效的增加短路電流將效率提升。
研究中,我們更將此奈米結構化的銦參雜氧化錫製作於軟性基 板上,而此種結構化基板同樣也可將太陽能效率有效從 1 % 替升至 1.3 %,總體提升效率約為 30 %。

關鍵字

砷化銦 ； 銦參雜氧化錫 ； 奈米線 ； 成長機制 ； 奈米結構 ； 場效電晶體

並列摘要

The thesis includes two parts: catalytic effect on InAs nanowire growth and polymer solar cell on large scale array nanobowl In doped tin oxide nanostructure for high performance electron devices.
The influence of the catalyst materials on the electron transport behaviors of InAs nanowires (NWs) grown by a conventional vapor transport technique has been investigated. Utilizing the NW field-effect transistor (FET) device structure, ~20 % and ~80 % of Au-catalyzed InAs NWs exhibit strong and weak gate dependence characteristics, respectively. In contrast, ~98 % of Ni-catalyzed InAs NWs demonstrate an uniform n-type behavior with strong gate dependence, resulting in an average OFF current of ~10-10 A and a high ION/IOFF ratio of >104. The non-uniform device performance of Au-catalyzed NWs is mainly attributed to the non-stoichiometric composition of the NWs grown owing to different segregation behavior compared to that of Ni-catalyzed NWs, which is further supported with the in-situ transmission electron microscopy studies. These distinct electrical characteristics associated with different catalysts were further investigated by the first principle calculation. Moreover, top-gated and large-scale parallel-array FETs were fabricated with Ni-catalyzed NWs by contact printing and channel metallization techniques, which yield excellent electrical performance. The results shed light on the direct correlation of the device performance with the catalyst choice.
A two-dimensional nanobowl array (2D-NBRs) with a unique honeycomb nanostructure was demonstrated with controllable
VIII
morphologies synthesized by the Langmuir–Blodgett (LB) method. The periodicity of 2D-NBRs can be controlled by utilizing different diameters of polystyrene (PS) balls ranged from 500 nm, 870 nm, 1 m to 2 m. The reflectance measurements revealed that the planar structure with a poly(3-hexylthiophene) (P3HT)/(6,6)-phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction layer as an active layer exhibits a reflectance of ~20 %, while a significant reduction of the reflectance , 5– 7 % can be achieved after formation of 2D-NBRs at a PS ball diameter of 500 nm, which perfectly matches simulation results. From experimental results, the highest efficiency of 5.4 % with a filling factor of 66 % was achieved for the device with 2D-NBRs at PS ball diameter of 870 nm. Compared to a planar device with an efficiency of 3.9 %, a maximum enhancement of ~40 % can be achieved owing to the enhancement of Jsc because of unique honeycomb geometry, which exhibits a broadband and omnidirectional light harvesting behavior. Furthermore, a flexible solar cell was demonstrated with an enhanced efficiency of 30 % for a planar structure of 1 % to 1.3 % for 2D-NBRs structure.

並列關鍵字

InAs ； ITO ； nanowire ； growth mechanism ； nanostructure ； FET

參考文獻

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