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MgZnO合金具有可覆盖日盲紫外波段的禁带宽度和晶格匹配的单晶衬底,是理想的日盲紫外探测材料。由于MgO和ZnO分属立方相和六角相,分相问题使高质量单一相MgZnO难以获得。热处理是提高薄膜结晶质量的有效手段。利用MOCVD方法制备了单一立方相Mg0.57Zn0.43O合金薄膜,研究了薄膜的退火行为对薄膜结构和光学性能的影响。研究发现,450℃的原生样品经过550,650,750,850℃氧气氛退火后,薄膜的结晶特性和表面形貌得到明显的改善。随着退火温度的增加,薄膜吸收截止边逐渐蓝移,带隙展宽。X光电子能谱分析发现,随着退火温度增加,Zn含量逐渐减小,这种现象被归结为组分蒸汽压的差异。在退火温度达到950℃时,样品发生了分相,出现了低Mg含量的六角相MgZnO。
MgZnO alloy with a bandgap and lattice matched single crystal substrate that can cover the UVL band is the ideal solar blind UV detection material. Since MgO and ZnO belong to the cubic phase and the hexagonal phase, the phase separation problem makes high quality single phase MgZnO difficult to obtain. Heat treatment is an effective means to improve the quality of thin films. Single-phase Mg0.57Zn0.43O alloy films were prepared by MOCVD and the effects of annealing behavior on the structure and optical properties of the films were investigated. The results show that the crystallinity and surface morphology of the samples after 450 ℃ annealing at 550, 650, 750 and 850 ℃ are obviously improved. With the increase of annealing temperature, the absorption edge of the film gradually blue-shifted and the band gap widened. X-ray photoelectron spectroscopy analysis found that as the annealing temperature increases, the Zn content decreases gradually. This phenomenon is attributed to the differences in the vapor pressures of the components. When the annealing temperature reached 950 ℃, the samples were phase-separated and hexagonal MgZnO with low Mg content appeared.