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采用二步阳极氧化法在草酸溶液中制备了多孔阳极氧化铝(PAA)薄膜。借助于扫描电子显微镜(SEM)分析了多孔阳极氧化铝薄膜的微观形貌。结果发现,在其表面孔径为30~40nm的六边形孔洞分布均匀,且垂直于表面平行生长。依据PAA透射光谱的实验数据,采用极值包络线算法计算出了PAA薄膜的复折射率以及光学能隙等光学常数。通过分析吸收系数与入射光子能量之间的关系发现,PAA薄膜具有直接带隙半导体的电子结构特征,而且由理论计算得到的PAA的带隙能与其光致发光谱的峰位能是一致的。
Porous anodic aluminum oxide (PAA) thin films were prepared by two-step anodic oxidation in oxalic acid solution. The microstructure of porous anodic aluminum oxide films was analyzed by means of scanning electron microscopy (SEM). The results showed that hexagonal holes with a surface pore size of 30-40 nm were uniformly distributed and grow parallel to the surface. Based on the experimental data of PAA transmission spectra, the complex refractive index and the optical constants of PAA films were calculated using the extreme envelope algorithm. The relationship between the absorption coefficient and the incident photon energy is analyzed. It is found that the PAA film has the electronic structure of the direct band gap semiconductor, and the calculated band gap energy of the PAA is in good agreement with that of the photoluminescence peak.