Seeding Atomic Layer Deposition of High-k Dielectrics on Epitaxial Graphene with Organic Self-Assembled Monolayers
Seeding Atomic Layer Deposition of High-k Dielectrics on Epitaxial Graphene with Organic Self-Assembled Monolayers
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DOI：
10.1021/nn201414d
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发表时间：
2011-06-01
期刊：
影响因子：
17.1
通讯作者：
Hersam, Mark C.
中科院分区：
文献类型：
--
作者：
Alaboson, Justice M. P.;Wang, Qing Hua;Hersam, Mark C.
高性能石墨烯基纳电子学的发展需要超薄、无针孔的高k介电薄膜与石墨烯在晶片规模上的集成。在本论文中，我们证明了PtCDA自组装单分子膜(PTCDA)是在碳化硅(0001)上外延石墨烯上沉积HfO2和Al_2O_3原子层的有效有机种子层。PTCDA是在超高真空中通过升华沉积的，分子分辨扫描隧道显微镜显示其具有高度的有序性和低的缺陷密度。相同的AID条件会导致在裸露的石墨烯上进行不完全和粗糙的介质沉积，而PTCDA种子层提供的化学功能可以生成高度均匀的Mnidrmal薄膜。用原子力显微镜、椭偏仪、横截面扫描电子显微镜和X射线光电子能谱对介电薄膜的形貌和化学结构进行了表征，而高分辨率的X射线反射率测量表明，在AID后，底层的石墨烯保持不变。使用PTCDA种子层，采用3 nm氧化铝和10 nm HfO2介质叠层制备的金属氧化物石墨烯电容器在1V偏压下显示出接近700nF/cm(2)的高电容值和接近5×10(-9)A/cm(2)的低泄漏电流。这些结果证明了升华有机自组装单分子膜作为石墨烯纳米电子器件中高k介电薄膜的种子层的可行性。
The development of high-performance graphene-based nanoelectronics requires the Integration of ultrathin and pinhole-free high-k dielectric films with graphene at the wafer scale. Here, we demonstrate that self-assembled monolayers of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) act as effective organic seeding layers for atomic layer deposition (ALD) of HfO2 and Al2O3 on epitaxial graphene on SiC(0001). The PTCDA is deposited via sublimation in ultrahigh vacuum and shown to be highly ordered with low defect density by molecular-resolution scanning tunneling microscopy. Whereas identical AID conditions lead to incomplete and rough dielectric deposition on bare graphene, the chemical functionality provided by the PTCDA seeding layer yields highly uniform and Mnidrmal films. The morphology and chemistry of the dielectric films are characterized by atomic force microscopy, ellipsometry, cross-sectional scanning electron microscopy, and X-ray photoelectron spectroscopy, while high-resolution X-ray reflectivity measurements Indicate that the underlying graphene remains Intact following AID. Using the PTCDA seeding layer, metal-oxide-graphene capacitors fabricated with a 3 nm Al2O3 and 10 nm HfO2 dielectric stack show high capacitance values of similar to 700 nF/cm(2) and low leakage currents of similar to 5 x 10(-9) A/cm(2) at 1 V applied bias. These results demonstrate the viability of sublimated organic self-assembled monolayers as seeding layers for high-k dielectric films in graphene-based nanoelectronics.