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利用脉冲激光沉积技术,通过改变沉积过程中的氧气压力,在蓝宝石(0001)基片上制备了一系列ZnMgO合金.通过X射线衍射、反射和透射光谱以及室温和变温荧光光谱,对薄膜的结构和光学性能进行了系统地表征,分析了工作气压对ZnMgO合金薄膜的结晶质量及光学特性的影响.研究结果表明:随着沉积环境中氧气压力的增大,ZnMgO薄膜的结晶质量下降,富氧环境下,与蓝宝石晶格平行的ZnO晶粒的出现是导致薄膜结晶质量下降的主要原因;相对于本征ZnO,不同氧气环境下沉积的ZnMgO薄膜的紫外荧光峰均出现了不同程度的蓝移.随着工作气压的增大,ZnMgO薄膜的紫外荧光峰峰位从3.374eV逐渐红移到3.332eV,氧气压力增加导致的ZnMgO薄膜中Mg含量的减少是紫外荧光峰红移主要原因;与ZnO薄膜相比,ZnMgO薄膜的紫外PL光谱存在着明显的宽化现象,而且主要由两个荧光峰构成,分别对应为束缚激子复合过程和局域激子复合过程;ZnMgO薄膜中束缚激子的激活能较大,并随薄膜沉积环境中氧气压力的增加有逐渐增大的趋势.
A series of ZnMgO alloys were prepared on sapphire (0001) substrate by changing the pressure of oxygen in the deposition process by pulsed laser deposition technique. The structure and properties of the films were characterized by X-ray diffraction, reflection and transmission spectra, room temperature and temperature- Optical properties were systematically characterized and the effects of operating pressure on the crystalline quality and optical properties of ZnMgO films were analyzed.The results show that the crystalline quality of ZnMgO thin films decreases with the increase of oxygen pressure in the depositional environment, , The appearance of ZnO grains parallel to the sapphire crystal is the main reason for the decrease of the crystalline quality of the films. Compared with the intrinsic ZnO, the UV fluorescence peaks of ZnMgO films deposited under different oxygen environments all show different degrees of blue-shift. With the increase of working pressure, the peak of ultraviolet fluorescence peak of ZnMgO thin film red-shifted from 3.374eV to 3.332eV. The decrease of Mg content in ZnMgO film caused by the increase of oxygen pressure was the main reason for the red-shift of UV fluorescence peak. In contrast, the UV-PL spectra of ZnMgO thin films are obviously widened, and mainly consist of two fluorescence peaks corresponding to the bound excitons complex And the process of local exciton recombination. The activation energy of bound excitons in ZnMgO films is larger and tends to increase with the increase of oxygen pressure in the film depositional environment.