Laboratorio MDM, IMM-CNR, via C. Olivetti 2, I-20864, Agrate Brianza (MB), Italy.
Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, I-16146, Genova (Ge), Italy.
Adv Mater. 2017 May;29(19). doi: 10.1002/adma.201605785. Epub 2017 Mar 10.
Manipulating the anisotropy in 2D nanosheets is a promising way to tune or trigger functional properties at the nanoscale. Here, a novel approach is presented to introduce a one-directional anisotropy in MoS nanosheets via chemical vapor deposition (CVD) onto rippled patterns prepared on ion-sputtered SiO /Si substrates. The optoelectronic properties of MoS are dramatically affected by the rippled MoS morphology both at the macro- and the nanoscale. In particular, strongly anisotropic phonon modes are observed depending on the polarization orientation with respect to the ripple axis. Moreover, the rippled morphology induces localization of strain and charge doping at the nanoscale, thus causing substantial redshifts of the phonon mode frequencies and a topography-dependent modulation of the MoS workfunction, respectively. This study paves the way to a controllable tuning of the anisotropy via substrate pattern engineering in CVD-grown 2D nanosheets.
在二维纳米片中人为引入各向异性是一种在纳米尺度上调节或触发功能特性的很有前途的方法。在这里，提出了一种新的方法，通过化学气相沉积（CVD）将各向异性引入到波纹图案上的 MoS 纳米片中，该波纹图案是在离子溅射的 SiO2/Si 衬底上制备的。MoS 的光电性能在宏观和纳米尺度上都受到波纹 MoS 形态的强烈影响。特别是，观察到依赖于极化方向的各向异性声子模式。此外，波纹形态导致应变和电荷掺杂在纳米尺度上的局部化，从而导致声子模式频率的显著红移以及 MoS 功函数的形貌依赖性调制。本研究为通过 CVD 生长的二维纳米片中的衬底图案工程来控制各向异性铺平了道路。
