Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", 15310 Athens, Greece.
University of Athens , Department of Physics, Section of Solid State Physics, 15684 Athens, Greece.
ACS Appl Mater Interfaces. 2016 Jan 27;8(3):1836-41. doi: 10.1021/acsami.5b09743. Epub 2016 Jan 15.
Molecular beam epitaxy of 2D metal TaSe2/2D MoSe2 (HfSe2) semiconductor heterostructures on epi-AlN(0001)/Si(111) substrates is reported. Electron diffraction reveals an in-plane orientation indicative of van der Waals epitaxy, whereas electronic band imaging supported by first-principles calculations and X-ray photoelectron spectroscopy indicate the presence of a dominant trigonal prismatic 2H-TaSe2 phase and a minor contribution from octahedrally coordinated TaSe2, which is present in TaSe2/AlN and TaSe2/HfSe2/AlN but notably absent in the TaSe2/MoSe2/AlN, indicating superior structural quality of TaSe2 grown on MoSe2. Apart from its structural and chemical compatibility with the selenide semiconductors, TaSe2 has a workfunction of 5.5 eV as measured by ultraviolet photoelectron spectroscopy, which matches very well with the semiconductor workfunctions, implying that epi-TaSe2 can be used for low-resistivity contacts to MoSe2 and HfSe2.
二维金属 TaSe2/二维 MoSe2（HfSe2）半导体异质结构的分子束外延在 epi-AlN(0001)/Si(111)衬底上进行了报道。电子衍射显示出面内取向，表明存在范德华外延，而基于第一性原理计算和 X 射线光电子能谱的电子能带成像则表明存在占主导地位的三角棱柱 2H-TaSe2 相和少量八面体配位 TaSe2，其存在于 TaSe2/AlN 和 TaSe2/HfSe2/AlN 中，但在 TaSe2/MoSe2/AlN 中明显不存在，表明 TaSe2 在 MoSe2 上的生长具有更好的结构质量。除了与硒化物半导体在结构和化学上的兼容性外，TaSe2 的功函数为 5.5 eV，这是通过紫外光电子能谱测量得到的，与半导体功函数非常匹配，这意味着 epi-TaSe2 可以用于 MoSe2 和 HfSe2 的低电阻接触。
