电子束共蒸发Al2O3-La2O3和ZrO2-Ta2O5复合薄膜的介电性能研究

Al2O3、ZrO2、Ta2O5和La2O3薄膜在栅介质、无机EL介质和光学薄膜方面有着重要用途，但对其复合薄膜介电性能方面的研究很少。文章采用电子束共蒸发法制备了厚度分别为414nm和143nm的Al2O3-La2O3（ALO）和ZrO2-Ta2O5（ZTO）复合薄膜，用Sawyer—Tower电路测得介电常数分别为17和34，反映介电损耗的参数△Vy分别为0．013V和0．56V，击穿场强分别为128MV／m和175MV／m，在50MV／m场强下，ALO的正、反向漏电流密度分别为3．1×10-5／cm2和4．1×10-5A／cm2，ZTO的正、反向漏电流密度分别为3．9×10-5／cm2和3．7×10-5A／cm2。另外，实验还与电子束蒸发和反应溅射制备的Al2O3、ZrO2、Ta2O5的介电性能做了比较，结果表明，上述复合薄膜单独作为无机EL绝缘层是不合适的。

Study on the Dielectric Properties of Al2O3-La2O3 and ZrO2-Ta2O5 Composite Thin Films Deposited by Electron Beam Coevaporation

Alumina, zirconia, tantalum pentoxide and lanthanum oxide are important diele- ctrics for gate materials in semiconductors, for insulators in inorganic electroluminescence and for thin films in optics, however, little investigation has focused on their composite thin films. Al2O3-La2O3 (ALO) and ZrO2-Ta2O5 (ZTO) composite thin films with thicknesses of 414nm and 143nm, respectively, were prepared by electron beam co-evaporation and their dielectric performance was investigated with Sawyer-Tower circuit in this article. The relative dielectric constants are measured to be 17 and 34, while the △Vy values, which are proportional to loss tangent, are 0.013V and 0.56V, the dielectric breakdown strengths are 128MV/m and 175MV/m, the forward and reverse leakage current densities at a field strength of 50MV/m are 3.1×10-5A/cm2 and 4.1×10-5A/cm2 for ALO and 3.9×10-5A/cm2 and 3.7×10-5A/cm2 for ZTO, respectively. Their dielectric properties were also compared to those of alumina, zirconia and tantalum pentoxide thin films fabricated by electron beam evaporation and reactive magnetron sputtering. It is also found that the composite thin films are inadequate for use as a single dielectric in inorganic electroluminescence.