Ultrafast carrier dynamics and third order nonlinear optical properties of aluminum doped zinc oxide (AZO) thin films
Ultrafast carrier dynamics and third order nonlinear optical properties of aluminum doped zinc oxide (AZO) thin films
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铝掺杂氧化锌（AZO）薄膜的超快载流子动力学和三阶非线性光学特性
DOI：
10.1016/j.optmat.2017.03.009
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发表时间：
2017-04-01
影响因子：
3.9
通讯作者：
Yuan, Ping
中科院分区：
文献类型：
--
作者：
Htwe, Zin Maung;Zhang, Yun-Dong;Yuan, Ping
采用射频/直流磁控溅射技术在蓝宝石（Al 2 O3）衬底上制备了不同直流溅射功率（2、6、8和10 W）的掺铝氧化锌（AZO）薄膜。溅射的薄膜在350摄氏度下退火，以提高晶体质量。利用X射线衍射仪（XRD）、扫描电子显微镜（SEM）和IJV-VIS光谱仪对AZO薄膜的结构和光学性能进行了系统的分析。XRD分析表明，溅射薄膜均为六方纤锌矿结构。SEM图像显示，Al掺杂后ZnO的平均晶粒尺寸增大，这与XRD计算值相一致。所有薄膜在可见光区都具有很高的透光率，并且光学带隙值随着Al浓度的增加而增加。利用飞秒泵浦-探测光谱技术研究了AZO的超快瞬态吸收。用三指数衰减函数拟合了动力学TA曲线，得到了超快和慢过程的衰减时间常数分别在皮秒和纳秒范围内。利用Z扫描技术研究了三阶非线性光学吸收系数和折射系数。所观察到的非线性系数增强与Al的浓度在ZnO。(C)2017爱思唯尔B. V.保留所有权利。
Aluminum doped zinc oxide (AZO) thin films were fabricated by simultaneous RF/DC magnetron sputtering technique on sapphire (Al2O3) substrate with different DC sputtering power 2, 6, 8 and 10 W respectively. The sputtered thin films were annealed at 350 degrees C in order to improve the crystal quality. AZO thin films are systematically analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and IJV-VIS spectrometer for structural and optical properties. XRD patterns show that all sputtered thin films are well crystallized with hexagonal wurtzite structure. SEM images reveal the average crystallite sizes are increased after doping Al in ZnO which agreed with the calculated values from XRD. All thin films possess high optical transmittance in visible region and optical band gap values are relatively increased with Al concentration. The ultrafast transient absorption (TA) of AZO was analyzed by femtosecond pump-probe spectroscopy. The kinetic TA curves were fitted by tri-exponential decay function and obtained decay time constants are found to be in few picosecond and nanosecond range for ultrafast and slow processes respectively. Third order nonlinear optical absorption and refraction coefficients were investigated by using Z-scan technique. The observed nonlinear coefficients are enhanced with Al concentration in ZnO. (C) 2017 Elsevier B.V. All rights reserved.