Lian Jiqing, Zhang Dawei, Hong Ruijin, Qiu Peizhen, Lv Taiguo, Zhang Daohua
Engineering Research Center of Optical Instrument and System, Ministry of Education and Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China.
School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore.
Nanomaterials (Basel). 2018 Nov 7;8(11):922. doi: 10.3390/nano8110922.
Defect-induced tunable permittivity of Epsilon-Near-Zero (ENZ) in indium tin oxide (ITO) thin films via annealing at different temperatures with mixed gases (98% Ar, 2% O₂) was reported. Red-shift of λ (Epsilon-Near-Zero wavelength) from 1422 nm to 1995 nm in wavelength was observed. The modulation of permittivity is dominated by the transformation of plasma oscillation frequency and carrier concentration depending on Drude model, which was produced by the formation of structural defects and the reduction of oxygen vacancy defects during annealing. The evolution of defects can be inferred by means of X-ray diffraction (XRD), atomic force microscopy (AFM), and Raman spectroscopy. The optical bandgaps (E) were investigated to explain the existence of defect states. And the formation of structure defects and the electric field enhancement were further verified by finite-difference time domain (FDTD) simulation.
报道了通过在不同温度下用混合气体（98%Ar，2%O₂）对氧化铟锡（ITO）薄膜进行退火，缺陷诱导的近零介电常数（ENZ）的可调谐介电常数。观察到波长λ（近零介电常数波长）从1422nm红移到1995nm。根据德鲁德模型，介电常数的调制主要由等离子体振荡频率和载流子浓度的变化决定，这是由退火过程中结构缺陷的形成和氧空位缺陷的减少所产生的。可以通过X射线衍射（XRD）、原子力显微镜（AFM）和拉曼光谱来推断缺陷的演变。研究了光学带隙（E）以解释缺陷态 的存在。并通过时域有限差分（FDTD）模拟进一步验证了结构缺陷的形成和电场增强。
