射频磁控反应溅射制备的Ag_2O薄膜的椭圆偏振光谱研究

Spectroscopic ellipsometry study of the Ag_2O film deposited by radio-frequency reactive magnetron sputtering

Ag_2O薄膜在新型超高存储密度光盘和磁光盘方面具有潜在的应用前景.利用射频磁控反应溅射技术,通过调节衬底温度在沉积气压为0.2 Pa、氧氩比为2:3的条件下制备了一系列Ag_2O薄膜.利用通用振子模型(包括1个Tauc-Lorentz振子和2个Lorentz振子)拟合了薄膜的椭圆偏振光谱.在1.5-3.5 eV能量区间,薄膜的折射率在2.2-2.7之间,消光系数在0.3-0.9之间.在3.5-4.5 eV能量区间,薄膜呈现了明显的反常色散,揭示Ag_2O薄膜的等离子体振荡频率在3.5-4.5 eV之间.随着衬底温度的升高,薄膜的光学吸收边总体上发生了红移,该红移归结于薄膜晶格微观应变随衬底温度的升高而增大.Ag_2O薄膜的光学常数表现出典型的介质材料特性.

Ag2O film has a potential application in high-density optical and magneto-optical disks. In this paper, a series of Ag2O films is deposited by radio-frequency reactive magnetron sputtering at different substrate temperatures, a deposition pressure of 0.2 Pa and an oxygen flow ratio of 2：3. The spectroscopic ellipsometry spectra of the films are fitted by using a general oscillator model （including one Tanc-Lorentz oscillator and two Lorentz oscillators）. In an energy range between 1.5 eV and 3.5 eV, the refractive index and extinctive coefficient of the film are in ranges between 2.2 and 2.7, and between 0.3 and 0.9, respectively. The film indicates a clear abnormal dispersion in an energy range of 3.5 eV and 4.5 eV, meaning that the plasma oscillator frequency of the film is in this energy range. A redshift of the absorption edge of the film occurs with substrate temperature increasing, which can be attributed to the increased lattice strain. The optical constants of the film clearly show the dielectric properties.