| 摘要: | 本論文研究一系列不同碳鏈長度之磷酸自組性單分子層(Phosphonic acid self-assembled molecules, PA SAMs)應用於p-type有機半導體dinaphtho[2,3-b:2’,3’-f]thieno[3,2-b](DNTT)之橫向和垂直電晶體以及DNTT結合無機半導體ZnO之雙載子電晶體，探討PA SAMs在金屬氧化絕緣層、電極、無機半導體的表面處理對DNTT薄膜結構與電性的影響。
在DNTT橫向電晶體中，發現以dodecyl-PA SAM (C12)進行Al2O3絕緣層表面處理可獲得最高的電洞遷移率 3.9 cm2/Vs，相較於無表面處理之Al2O3提升6倍。在DNTT垂直電晶體中，發現利用C12進行開孔金源極表面處理也獲得最高的電洞遷移率，而在ZnO/DNTT雙載子電晶體在電性上也有類似趨勢。
進一步透過原子力顯微鏡、X光繞射儀、近緣X光吸收細微結構分析表面形貌、晶格結構、有機分子傾角差異，證實DNTT沉積在C12處理之Al2O3將形成較大的晶粒結構和較少的晶界，為造成橫向和垂直方向電荷遷移率提昇之主要原因。此外，透過紫外光電子能譜量測也發現在DNTT垂直電晶體之開孔金源極進行較長碳鏈的PA SAMs處理會略微增加注入能障，但對於電晶體電流的影響並不明顯。在ZnO/DNTT雙載子電晶體中，C12處理的ZnO表面也有助於提昇DNTT電洞遷移率和減少磁滯現象，亦代表減少的表面缺陷態。
總體而言，PA SAMs可廣泛的應用於金屬氧化介電材料、金屬、和金屬氧化半導體表面修飾，適當的PA SAMs可有效的控制上方沉積的有機薄膜結構，近而提升不同元件之電性表現。
;This thesis investigates the application of a series of phosphonic acid self-assembled monolayers (PA SAMs) with different alkyl chain lengths to p-type organic semiconductors dinaphtho[2,3-b:2′,3 ′-f]thieno[3,2-b] (DNTT) as lateral and vertical transistors and DNTT combined with the inorganic semiconductor ZnO as ambipolar transistors to investigate the effect of PA SAMs on the structure and electrical properties of DNTT films by surface modification of metal oxide dielectric layers, electrodes, and inorganic semiconductors.
In the DNTT lateral transistors, the highest hole mobility of 3.9 cm2/Vs was found to be achieved by surface modification of the Al2O3 insulator layer with dodecyl PA SAM (C12), which is 6 times higher than Al2O3 without surface modification. In the DNTT vertical transistors, the highest hole mobility was found to be achieved if the perforated Au source electrode were modified with C12, and a similar trend was observed in the ZnO/DNTT ambipolar transistors in terms of electrical properties.
Further analyses of morphology, crystallinity and molecular orientation by Atomic Force Microscope (AFM), X-Ray Diffraction (XRD) and Near-Edge X-ray Absorption Fine Structure (NEXAFS) confirm that deposition of DNTT on C12-modified Al2O3 forms larger grain structures and fewer grain boundaries, which is the main cause for the increased charge transport in both the lateral and vertical directions. In addition, UV photoelectron spectroscopy (UPS) measurements also show that modification of PA SAMs with longer alkyl chains in DNTT perforated Au source electrode slightly increases the injection barrier, but the effect on the transistor current is not significant.
In ZnO/DNTT ambipolar transistors, the C12-modified ZnO surface also contributes to improved DNTT hole mobility and reduced hysteresis, and represents a reduction in surface defect states.
Overall, we show that PA SAMs can be widely applied for surface modification of metal oxide dielectric materials, metals, and metal oxide semiconductors. Appropriate PA SAMs can effectively control the organic film structure deposited on top, thus enhancing the electrical performance of different device. |
