Sagar Srikrishna, Mohammadian Navid, Park Seonghyun, Majewski Leszek A, Das Bikas C
Emerging Nanoelectronic Devices Research Laboratory (eNDR Lab), School of Physics, Indian Institute of Science Education and Research Thiruvananthapuram (IISER TVM), Maruthamala PO, Vithura, Thiruvananthapuram 695551, Kerala, India.
Nanotechnology. 2020 Apr 3;31(25):255705. doi: 10.1088/1361-6528/ab7fd1. Epub 2020 Mar 13.
Anodically oxidized, ultra-thin (d < 10 nm) aluminium films emerge as the dielectric of choice for low-cost thin film capacitors (TFCs), thin film transistors (TFTs), and bio- and chemical sensors. In this work, the dielectric properties of ultra-thin aluminium oxide films grown by anodization in aqueous solutions of citric acid (CA) have been studied. It is observed that the electrolyte strength variation from 0.1 mM to 1000 mM has virtually no influence on the chemical composition, surface morphology and the dielectric properties of the fabricated alumina films. The anodized films are very smooth having RMS area roughness around ∼5 Å. This was further improved after deposition of n-octadecyltrichlorosilane (OTS) self-assembled monolayer (SAM) to ∼4 Å. Also, the XRD and elemental analysis using EDS and XPS unambiguously confirms that the obtained oxide films are amorphous, stoichiometric AlO without any carbon contamination. The fabricated Al/AlO/Al MIM capacitors show almost ideal capacitor characteristics from 10 Hz to 100 kHz. It has been found that the OTS coating does not only improve the capacitor frequency response further but also reduces the leakage current through the dielectric layer by passivating reactive dangling bonds on the oxide surface. As a result of the favourable properties of the anodized AlO/OTS films, high-performance, low threshold voltage organic thin film transistors (OTFTs) operating below 1 V are successfully demonstrated.
阳极氧化的超薄（d < 10 nm）铝膜成为低成本薄膜电容器（TFC）、薄膜晶体管（TFT）以及生物和化学传感器的首选电介质。在这项工作中，研究了在柠檬酸（CA）水溶液中通过阳极氧化生长的超薄氧化铝膜的介电性能。观察到电解质强度从0.1 mM变化到1000 mM对所制备氧化铝膜的化学成分、表面形貌和介电性能几乎没有影响。阳极氧化膜非常光滑，均方根面积粗糙度约为5 Å。在沉积正十八烷基三氯硅烷（OTS）自组装单分子层（SAM）后，粗糙度进一步改善至约4 Å。此外，使用能谱仪（EDS）和X射线光电子能谱仪（XPS）进行的X射线衍射（XRD）和元素分析明确证实，所获得的氧化膜是无定形的化学计量比AlO，没有任何碳污染。所制备的Al/AlO/Al金属 - 绝缘体 - 金属（MIM）电容器在10 Hz至100 kHz范围内显示出几乎理想的电容器特性。已发现OTS涂层不仅进一步改善了电容器的频率响应，还通过钝化氧化物表面的反应性悬空键减少了通过介电层的漏电流。由于阳极氧化的AlO/OTS膜具有良好的性能，成功展示了工作电压低于1 V的高性能、低阈值电压有机薄膜晶体管（OTFT）。
