Johns James E, Karmel Hunter J, Alaboson Justice M P, Hersam Mark C
Departments of Materials Science and Engineering, Chemistry, and Medicine, Northwestern University, Evanston IL, 60208-3108, USA.
J Phys Chem Lett. 2012 Jul 11;3(15):1974-1979. doi: 10.1021/jz300802k.
The superlative electronic properties of graphene suggest its use as the foundation of next generation integrated circuits. However, this application requires precise control of the interface between graphene and other materials, especially the metal oxides that are commonly used as gate dielectrics. Towards that end, organic seeding layers have been empirically shown to seed ultrathin dielectric growth on graphene via atomic layer deposition (ALD), although the underlying chemical mechanisms and structural details of the molecule/dielectric interface remain unknown. Here, confocal resonance Raman spectroscopy is employed to quantify the structure and chemistry of monolayers of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) on graphene before and after deposition of alumina with the ALD precursors trimethyl aluminum (TMA) and water. Photoluminescence measurements provide further insight into the details of the growth mechanism, including the transition between layer-by-layer growth and island formation. Overall, these results reveal that PTCDA is not consumed during ALD, thereby preserving a well-defined and passivating organic interface between graphene and deposited dielectric thin films.
石墨烯卓越的电子特性表明其可作为下一代集成电路的基础材料。然而，此应用需要精确控制石墨烯与其他材料之间的界面，尤其是常用作栅极电介质的金属氧化物。为此，经验表明有机籽晶层可通过原子层沉积（ALD）在石墨烯上引发超薄电介质生长，尽管分子/电介质界面的潜在化学机制和结构细节仍不为人所知。在此，利用共焦共振拉曼光谱对用ALD前驱体三甲基铝（TMA）和水沉积氧化铝之前和之后，石墨烯上的3,4,9,10 - 苝四羧酸二酐（PTCDA）单层的结构和化学性质进行量化。光致发光测量进一步深入了解了生长机制的细节，包括逐层生长和岛状形成之间的转变。总体而言，这些结果表明PTCDA在ALD过程中未被消耗，从而在石墨烯与沉积的介电薄膜之间保留了明确且具有钝化作用的有机界面。
