The present manuscript investigated the effect of thermal annealing at 150 °C (below Tg) and 250 °C (above Tg) on the nonlinear as well as linear optical parameters and structural changes of the thermally evaporated As35Se65 thin films. The structural investigation was done by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, whereas the surface morphology was studied by field emission scanning electron microscopy. The optical transmission and reflection spectra over the wavelength range 500–1200 nm were used to calculate the optical parameters. The optical energy gap, Urbach energy, optical density, skin depth, Tauc parameters for the as-deposited and annealed As35Se65 films were estimated and discussed in terms of density of defect states and disorders. The indirect optical energy gap decreased for 150 °C annealed film and abruptly increased for 250 °C annealed film as compared with the as-prepared film. The Swanepoel envelope method, WDD model, and Sellemeire postulates were employed for analysis of refractive index, static refractive index, dispersion energy, oscillator wavelength, oscillator energy, and dielectric constant. The non-linear refractive index and third-order susceptibility were also estimated with the help of empirical relations which showed opposite changes for the two annealing temperatures. The tunable optical properties can be applied for several optoelectronic application.

中文翻译：

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在高于和低于 Tg 退火时 As35Se65 薄膜中线性和非线性光学参数的切换

本手稿研究了 150 °C（低于 Tg）和 250 °C（高于 Tg）的热退火对热蒸发 As35Se65 薄膜的非线性和线性光学参数和结构变化的影响。通过X射线衍射、拉曼光谱、X射线光电子能谱进行结构研究，而通过场发射扫描电子显微镜研究表面形貌。500-1200 nm 波长范围内的光透射和反射光谱用于计算光学参数。根据缺陷状态和障碍的密度估计和讨论了沉积和退火的 As35Se65 薄膜的光能隙、Urbach 能量、光密度、趋肤深度、Tauc 参数。与制备的薄膜相比，150°C 退火薄膜的间接光能隙减小，250°C 退火薄膜的间接光能隙突然增加。Swanepoel 包络法、WDD 模型和 Sellemeire 假设用于分析折射率、静态折射率、色散能量、振荡器波长、振荡器能量和介电常数。非线性折射率和三阶磁化率也在经验关系的帮助下估计，该关系显示两个退火温度的相反变化。可调光学特性可应用于多种光电应用。静态折射率、色散能量、振荡器波长、振荡器能量和介电常数。非线性折射率和三阶磁化率也在经验关系的帮助下估计，该关系显示两个退火温度的相反变化。可调光学特性可应用于多种光电应用。静态折射率、色散能量、振荡器波长、振荡器能量和介电常数。非线性折射率和三阶磁化率也在经验关系的帮助下估计，该关系显示两个退火温度的相反变化。可调光学特性可应用于多种光电应用。