Advanced Instrumentation Institute, Korea Research Institute of Standards and Science, 267 Gajeong-ro, Yuseong-gu, Daejeon, 305-340, Republic of Korea. Department of Advanced Device technology, University of Science and Technology, 267 Gajeong-ro, Yuseong-gu, Daejeon, 305-340, Republic of Korea.
Nanotechnology. 2017 Dec 15;28(50):505601. doi: 10.1088/1361-6528/aa972b.
Two-dimensional (2D) copper chalcogenides (Cu X where X = S, Se, Te) have had much attention regarding various applications due to their remarkable optical and electrical properties, abundance, and environmentally friendly natures. This work indicates that highly uniform Cu S (where 0 < x < 1) nanosheets can be obtained by the two-step method of Cu deposition by sputtering with precisely controlled and extremely low growth rate followed by vapor-phase sulfurization. The phase transformations of thin Cu S films upon the Cu seed layer thickness are investigated. A unique thickness-constrained synthesis process using vapor-phase sulfurization is employed here, which evolves from a vertical to lateral growth mechanism based on the optimization of the Cu seed layer thickness. Atomically thin 2D β-CuS film was successfully synthesized using the thinnest Cu seed film. We have systematically investigated the phase- and thickness-dependent optical properties of Cu S films at room temperature. Micro-photoluminescence (PL) spectroscopy reveals that the 2D β-CuS film possesses a direct band gap with an energy of 1.1 eV while the PL intensities are greatly suppressed in the multilayer Cu S (where 0 ≤ x < 1).
二维（2D）铜的硫属化物（CuX，其中 X = S、Se、Te）由于其显著的光学和电学性质、丰富性和环境友好性而备受关注，在各种应用中都有很大的关注。这项工作表明，通过溅射精确控制和极低生长速率的铜沉积的两步法，可以获得高度均匀的 CuS（其中 0<x<1）纳米片。研究了薄 CuS 薄膜在 Cu 种子层厚度上的相转变。这里采用了独特的基于气相硫化的厚度受限合成工艺，该工艺基于优化 Cu 种子层厚度，从垂直生长机制演变为横向生长机制。使用最薄的 Cu 种子膜成功合成了原子级薄的 2Dβ-CuS 薄膜。我们系统地研究了室温下 CuS 薄膜的相和厚度依赖性光学性质。微光致发光（PL）光谱表明，2Dβ-CuS 薄膜具有直接带隙，能量为 1.1eV，而在多层 CuS（其中 0≤x<1）中，PL 强度大大降低。
