Pacuski Wojciech, Grzeszczyk Magdalena, Nogajewski Karol, Bogucki Aleksander, Oreszczuk Kacper, Kucharek Julia, Połczyńska Karolina E, Seredyński Bartłomiej, Rodek Aleksander, Bożek Rafał, Taniguchi Takashi, Watanabe Kenji, Kret Slawomir, Sadowski Janusz, Kazimierczuk Tomasz, Potemski Marek, Kossacki Piotr
Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura St. 5, 02-093 Warsaw, Poland.
National Institute for Materials Science, Tsukuba 305-0047, Ibaraki, Japan.
Nano Lett. 2020 May 13;20(5):3058-3066. doi: 10.1021/acs.nanolett.9b04998. Epub 2020 Mar 2.
Monolayer transition-metal dichalcogenides (TMDs) manifest exceptional optical properties related to narrow excitonic resonances. However, these properties have been so far explored only for structures produced by techniques inducing considerable large-scale inhomogeneity. In contrast, techniques which are essentially free from this disadvantage, such as molecular beam epitaxy (MBE), have to date yielded only structures characterized by considerable spectral broadening, which hinders most of the interesting optical effects. Here, we report for the first time on the MBE-grown TMD exhibiting narrow and resolved spectral lines of neutral and charged exciton. Moreover, our material exhibits unprecedented high homogeneity of optical properties, with variation of the exciton energy as small as ±0.16 meV over a distance of tens of micrometers. Our recipe for MBE growth is presented for MoSe and includes the use of atomically flat hexagonal boron nitride substrate. This recipe opens a possibility of producing TMD heterostructures with optical quality, dimensions, and homogeneity required for optoelectronic applications.
单层过渡金属二硫属化物（TMDs）表现出与窄激子共振相关的优异光学特性。然而，迄今为止，这些特性仅在通过诱导相当大的大规模不均匀性的技术所制备的结构中得到探索。相比之下，基本没有这一缺点的技术，如分子束外延（MBE），迄今为止仅产生了以相当大的光谱展宽为特征的结构，这阻碍了大多数有趣的光学效应。在此，我们首次报道了通过MBE生长的TMD展现出中性和带电激子的窄且可分辨的光谱线。此外，我们的材料展现出前所未有的光学特性高度均匀性，在数十微米的距离上激子能量变化小至±0.16毫电子伏特。我们给出了用于生长MoSe₂的MBE生长方法，包括使用原子级平整的六方氮化硼衬底。该方法为生产具有光电子应用所需光学质量、尺寸和均匀性的TMD异质结构开辟了可能性。
