铋含量的变化对Bi_xFeO_3薄膜微结构和光学性质的影响(英文)

Bismuth composition dependence of properties of Bi_x FeO_3 thin films

通过溶胶-凝胶技术在Si衬底上制备了x从0.80增大到1.20的Bi x FeO3薄膜样品.分析了Bi元素含量的改变对BFO薄膜微结构和光学性质的影响,表明在Bi缺失和Bi过量的Bi x FeO3薄膜样品中均出现了Bi2Fe4O9杂相和铁氧化物杂相,导致Bi x FeO3薄膜晶格的菱形扭曲结构发生变化.测试得到了薄膜的拉曼散射谱和椭圆偏振光谱,拉曼散射谱反映了Bi x FeO3薄膜样品中的振动模式明显受到x取值的影响.根据椭偏数据拟合得到的结果表明折射率在波长600 nm以下范围内随着x的减小而减小.而样品的禁带宽度从2.65 eV到2.76 eV,在x为1.05和1.10时得到最大值.

The Bix FeO3 films （0.80 ≤ x ≤ 1.20） were prepared by sol-gel technique on Si substrates. Effects of x variation on microstruetures and optical properties of the BixFeO3 films are reported. It is shown that in the films with both insuffi- cient and excess bismuth dosage, impurity phases such as Bi2 Fe4 09 and iron oxide appeared. Raman spectra of the films were presented in the spectral range of 50 - 800 cm^ -1. The refractive index （n） of the films decreases with increasing x at wavelength lower than 600 nm, the extinction coefficients （k） of all films were comparable. The bandgaps of the films changed from 2.65 eV to 2.76 eV.