磁控溅射制备不同组分La-Ni-O薄膜的研究

The composition dependence of the rf-magnetron sputtered La-Ni-O films

采用组合靶,利用射频磁控溅射在260℃的(111)Si片上面制备了不同Ni、La含量比的La Ni O薄膜。测试分析结果表明,在La含量较高时,薄膜为无定型结构,并且具有较大的电阻率。当Ni和La含量比>1∶1.44后,薄膜具有(100)择优取向的赝立方钙钛矿结构,同时具有金属导电特性。随着La过量的减少,晶面间距和面电阻都减小的很快,在Ni和La比例达到1∶1时,电阻率达到了最小值6.4Ω·μm,晶面间距也达到最小值0.389nm。随着Ni过量的增加,晶面间距和面电阻又逐步增大。在Ni过量较多时导致了NiO相和LNO(110)取向的出现。在晶面间距相同时,相对于La,Ni含量的过剩对薄膜导电性能具有较大的影响。文中对实验现象从LaNiO3薄膜的导电机理出发给出了比较合理的解释。

La-Ni-O thin films of different La and Ni concentration ratios were deposited on the (111)Si at a substrate temperature of 260℃ by a rf-magnetron sputtering system with a combined target. Results shows that the film is of amorphous structure when La content was too high. The film was with (100) preferred orientation and metallic electric conduction as the atomic concentration ratio of La to Ni was less than 1.44∶1. When the composition gets the stoichiometric composition (Ni∶La=1:1), the lattice constant and the sheet resistivity of the film reaches their minimums as 0.389nm and 6.4Ω·μm respectively. Then, as excessiveness of Ni increases, NiO phase appears and LaNiO_3(110) orientation is observed. The results also demonstrated that the excessiveness of Ni affected the conductivity more than that of La at the same lattice constant. A practicable explanation also was provided according to the conducting mechanism of LaNiO_3.