Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi, 110016, India.
Nanotechnology. 2017 Nov 3;28(44):445701. doi: 10.1088/1361-6528/aa87c5. Epub 2017 Aug 23.
Integration of a layered two-dimensional (2D) material with a non-2D material provides a platform where one can modulate and achieve the properties desired for various next-generation electronic and opto-electronic applications. Here, we investigated ZnTe nanoparticles/MoS hetero-interfaces with the thickness of the MoS varying from few to multilayer. High-resolution transmission electron microscopy was used to observe the crystalline behaviour of the ZnTe nanoparticles, while the number of MoS layers was investigated using Raman measurements. Spectroscopic ellipsometry (SE) analysis based on the five-layer fitting model was used to analyse the optical behaviour of the heterojunction, where the excitonic features corresponding to the MoS layers and absorption features due to the ZnTe nanoparticles are observed. From the Kelvin probe force microscopy (KPFM) measurements, the surface potential (SP) of the ZnTe nanoparticles/MoS is found to be different in comparison with the SP of the ZnTe nanoparticles and MoS, which is indicative of the charge transfer at the ZnTe nanoparticles/MoS hetero-interface. Various parameters obtained using SE and KPFM measurements were used to propose energy band alignments at the ZnTe nanoparticles/MoS hetero-interface. In addition, an interface photovoltage of 193 mV was obtained by carrying out KPFM measurements under illuminating condition.
将二维（2D）材料与非 2D 材料集成提供了一个平台，人们可以在其中调节和实现各种下一代电子和光电应用所需的特性。在这里，我们研究了 ZnTe 纳米粒子/MoS 异质界面，其中 MoS 的厚度从少数层到多层不等。高分辨率透射电子显微镜用于观察 ZnTe 纳米粒子的晶体行为，而使用拉曼测量研究了 MoS 层的数量。基于五层拟合模型的光谱椭圆偏振（SE）分析用于分析异质结的光学行为，其中观察到对应于 MoS 层的激子特征和由于 ZnTe 纳米粒子的吸收特征。从 Kelvin 探针力显微镜（KPFM）测量中发现，与 ZnTe 纳米粒子和 MoS 的表面电势（SP）相比，ZnTe 纳米粒子/MoS 的 SP 不同，这表明在 ZnTe 纳米粒子/MoS 异质界面处存在电荷转移。使用 SE 和 KPFM 测量获得的各种参数用于提出 ZnTe 纳米粒子/MoS 异质界面处的能带排列。此外，通过在光照条件下进行 KPFM 测量获得了 193 mV 的界面光电压。
