超薄BaSnO3薄膜及其场效应晶体管的磁控溅射制备技术研究

Single crystalline BaSnO3 thin film was attracted a lot attention since its high electron mobility, which may be used in high power electronic devices at high temperature environment. The preparation method normally used by other scientists was MBE or PLD constrained the development of BaSnO3 thin film TFT on high cost STO substrate in future application, as both methods rely heavily on the laser power and substrate size. Here, we propose a new method of preparing BaSnO3 thin film on commercial silicon substrate using magnetron sputtering technique, thus resolve the two constrains faced by other scientists. The BaSnO3 thin film was prepared by magnetron sputtering method for the first time, which has a electron mobility of 22 cm^2/V.s and the optical band gap was engineered between 3.4 eV and 4.0eV, and thin film TFT based on the sputtered- BaSnO3 thin film was also proved for the first time by control the conductivity of active layer. The field effect mobility will be improved to around 10 after dedicated control the preparation parameters. Oxygen vacancy and elemental ration may play the dominant role in this novel sputtered - BaSnO3 thin film transistors after further research.

以锡酸钡(BaSnO3)薄膜为激活层的薄膜晶体管在高功率和高温器件上具有良好的产业化前景。而现有的BaSnO3薄膜晶体管制备技术由于衬底限制、沉积工艺复杂，很难制备出大面积均匀的高性能锡酸钡薄膜。使用单晶硅衬底和磁控溅射方法制备BaSnO3薄膜晶体管，将使该材料更加易于工业化。通过前期课题的研究积累，我们初步掌握了锡酸钡薄膜磁控溅射制备的工艺参数对薄膜性能的影响规律，已经在硅片衬底上可控制备出晶态和非晶态的BaSnO3薄膜，薄膜的霍尔电子迁移率最高可达22 cm^2/V.s，光学带隙在3.4～4.0 eV 范围内可控调节，并且制备出有一定场效应迁移率的锡酸钡薄膜晶体管。预期通过进一步改进工艺即可在硅基衬底上制备出场效应迁移率大于1 cm^2/V.s的晶体管器件，更进一步实现场效应迁移率大于10 cm^2/V.s，并且进一步掌握磁控溅射工艺条件对BaSnO3薄膜中氧空位/元素计量比的影响。

作为一种新型的功能氧化物材料，锡酸钡具有高电子迁移率、宽光学带隙的特性，在透明导电氧化物薄膜、新型透明电子开关器件、气体检测器件等有重要的应用前景。本项目主要研究内容包括：锡酸钡薄膜的固相合成、锡酸钡薄膜磁控溅射制备、锡酸钡薄膜晶体管器件制备与性能分析等。研究过程中课题组发现通过磁控溅射工艺参数从而进行薄膜中氧空位浓度的控制，可以有效调控锡酸钡薄膜的导电特性，即可以分别可控制备出具有导电性能和绝缘性能的锡酸钡薄膜。利用硅基衬底，课题组第一次制备出了具有双层结构锡酸钡的薄膜晶体管器件，即利用绝缘锡酸钡替代硅基晶体管的栅极氧化硅材料，由此实现了半导体型锡酸钡作为晶体管器件的激活层，从而解决了硅基衬底锡酸钡薄膜与氧化层界面结构不匹配的核心问题。课题研究过程中制备出的锡酸钡薄膜最高电子迁移率大于20cm^2/V.S,场效应迁移率达到1cm^2/V.S，锡酸钡薄膜可见光波段光学透过率大于80%。除此之外，课题组还发现磁控溅射薄膜具备稀磁特性，薄膜的矫顽力可在28~78Oe范围内调控，饱和磁化强度可在2.9~69.4emu/g范围内调控。上述研究成果为锡酸钡薄膜的光学、电学、磁学等器件的应用开发奠定了基础。