Nucleation and growth of molybdenum disulfide grown by thermal atomic layer deposition on metal oxides
Nucleation and growth of molybdenum disulfide grown by thermal atomic layer deposition on metal oxides
复制标题
DOI：
10.1116/6.0002024
复制
发表时间：
2022-12
期刊：
影响因子：
--
通讯作者：
Jake Soares;Steven Letourneau;M. Lawson;A. Mane;Yu Lu;Yaqiao Wu;S. Hues;Lan Li;J. Elam;E. Graugnard
中科院分区：
文献类型：
--
作者：
Jake Soares;Steven Letourneau;M. Lawson;A. Mane;Yu Lu;Yaqiao Wu;S. Hues;Lan Li;J. Elam;E. Graugnard
为了更好地控制二硫化钼（MoS2）的热原子层沉积（ALD），在这里，我们报告了六氟化钼（MoF6）和硫化氢（H2S）与金属氧化物衬底从成核到几层薄膜的反应研究。在150、200和250 °C下进行的原位石英晶体微天平实验揭示了MoF6前体的温度依赖性成核行为，这归因于表面羟基浓度随温度的变化。原位傅里叶变换红外光谱结合非原位X射线光电子能谱（XPS）表明在成核过程中存在氧化钼和氟氧化钼物种。密度泛函理论计算另外支持这些物种的形成以及预测的金属氧化物到氟化物的转化。残余气体分析揭示了反应副产物，并结合实验和计算结果提供了建议的成核表面反应的见解。在附加ALD循环的情况下，傅里叶变换红外光谱表明在200 °C下13次循环后稳定的膜生长。XPS显示，较高的沉积温度导致在膜内的MoS2的较高分数。发现沉积温度在膜形态中起重要作用，在200 °C及以下获得非晶膜，而在250 °C观察到具有垂直片晶的层状膜。这些结果提供了一个更好的理解MoS2成核，这可以引导表面制备的沉积少层膜和推进MoS2集成到设备制造。
To enable greater control over thermal atomic layer deposition (ALD) of molybdenum disulfide (MoS2), here we report studies of the reactions of molybdenum hexafluoride (MoF6) and hydrogen sulfide (H2S) with metal oxide substrates from nucleation to few-layer films. In situ quartz crystal microbalance experiments performed at 150, 200, and 250 °C revealed temperature-dependent nucleation behavior of the MoF6 precursor, which is attributed to variations in surface hydroxyl concentration with temperature. In situ Fourier transform infrared spectroscopy coupled with ex situ x-ray photoelectron spectroscopy (XPS) indicated the presence of molybdenum oxide and molybdenum oxyfluoride species during nucleation. Density functional theory calculations additionally support the formation of these species as well as predicted metal oxide to fluoride conversion. Residual gas analysis revealed reaction by-products, and the combined experimental and computational results provided insights into proposed nucleation surface reactions. With additional ALD cycles, Fourier transform infrared spectroscopy indicated steady film growth after ∼13 cycles at 200 °C. XPS revealed that higher deposition temperatures resulted in a higher fraction of MoS2 within the films. Deposition temperature was found to play an important role in film morphology with amorphous films obtained at 200 °C and below, while layered films with vertical platelets were observed at 250 °C. These results provide an improved understanding of MoS2 nucleation, which can guide surface preparation for the deposition of few-layer films and advance MoS2 toward integration into device manufacturing.