磁控共溅射GaAs/SiO2细小纳米颗粒镶嵌材料的结构和非线性光学性质

应用磁控共溅射技术和后退火方法制备了GaAs/SiO2纳米颗粒镶嵌薄膜,并分别应用原子力显微镜、X射线衍射和卢瑟福背散射实验来观测薄膜的形貌、相结构和化学组分.结果表明GaAs纳米颗粒的平均直径很小(约为1.5～3.2nm),且均匀地分布于SiO2之中,薄膜中的GaAs和SiO2组分都符合化学计量关系.应用脉冲激光高斯光束对薄膜的光学非线性进行了Z扫描测试和分析.结果表明,薄膜的三阶光学非线性折射率系数和非线性吸收系数都由于量子限制效应而大大地增强,在非共振条件下,它们分别约为4×10-12m2/W和2×10-5m/W,在准共振的条件下,它们分别约为2×10-11m2/W和-1×10-4m/W.

Microstructure and Nonlinear Optical Properties of Very Small Size GaAs Nanogranulae Embedded in SiO_2 Matrix by Magnetron Co-Sputtering

Microstructure of GaAs/SiO2 nanogranular thin films fabricated by radio frequency magnetron co-sputtering technique and postannealing are investigated via atomic force microscope,X-ray diffraction,and Rutherford backscattering spectroscopy.The results show that GaAs nanocrystals with average diameters from 1.5nm to 3.2nm (depending on the annealing temperature) are uniformly dispersed in the SiO2 matrices.GaAs and SiO2 are found in normal stoichiometry in the films.The nonlinear optical refraction and nonlinear optical absorption are studied by Z-scan technique using a single Gaussian beam of pulse laser.The third-order nonlinear optical refractive index and nonlinear absorption coefficient are enhanced due to the quantum confinement effects and estimated to be 4×10-12m2/W and 2×10-5m/W respectively in nonresonant condition,while 2×10-11m2/W and -1×10-4m/W respectively in quasi-resonant condition.