利用溶胶凝胶工艺在SrTiO3单晶衬底上制备了一系列不同厚度的La0.7Ca0.3MnO3薄膜.X射线衍射表明这些薄膜均具有高度的择优取向性和结晶学质量.电学输运性质的研究结果凸显了膜厚的重要作用，主要归因于衬底施加的应力引起的薄膜晶格参数的改变.进一步的分析揭示，在厚度较小的膜中，小极化子的变程跃迁是高温下La0.7Ca0.3MnO3薄膜的主要导电机制，而在较厚的膜中，即使在低温下小极化子也是主要的载流子.

La0.7Ca0.3MnO3 thin films with various thicknesses were successfully fabricated on SrTiO3 single crystal substrates via sol-gel method. X-Ray diffraction manifests that all the films have highly preferential orientation. Electrical transport measurement shows a strong impact of film thickness on the physical properties of La0.7Ca0.3MnO3 thin films, which can be attributed to the change of lattice structure of the films substrate induced by strain. Further study indicates that in the films with small film thicknesses, variable range hopping of small polarons is the dominant transport process at high temperatures, and in those films with larger thicknesses small polarons are the predominant charge carriers even at very low temperatures.