通过旋涂法,采用不同浓度的前躯体制备了氧化锌多层膜,并制备了基于此多层膜的薄膜晶体管器件.实验证明,基于按照氧化锌前躯体浓度顺序为0.25、0.10和0.05 mol.L-1依次旋涂前躯体溶液制备的氧化锌薄膜的晶体管器件的载流子迁移率为0.02 cm.2V-.1s-1,高于按照浓度顺序为0.05、0.10和0.25 mol.L-1依次旋涂前躯体溶液制备的氧化锌薄膜的载流子迁移率(0.013 cm2.V-.1s-1).原子力显微镜(AFM)结果表明,前一种薄膜粗糙度的均方根值(rms)为3.95 nm,而后一种薄膜粗糙度的rms远远高于前者,为4.52 nm,这就说明了氧化锌薄膜的粗糙度对薄膜的半导体性质有很大的影响,这是由于平整的薄膜有利于形成理想的源/漏电极与半导体层的接触.在晶体管中,起传输作用的半导体层是靠近ZnO/SiO2界面处的几纳米的半导体层中的氧化锌晶粒,因此起始形成的氧化锌薄膜的结晶度影响着晶体管的性能.采用X射线衍射(XRD)测试了多层膜中起始形成的薄膜的结晶性能.对于前一种薄膜,起始形成的薄膜为多晶薄膜,而对于后一种薄膜,起始形成的薄膜是无定形薄膜.因此,粗糙度以及起始形成的薄膜的结晶度影响着多层半导体薄膜的性质.
In this paper,we describe multilayer ZnO thin films prepared by spin-coating precursor solutions of different concentrations.The multilayer ZnO thin films were employed as active layers in thin film transistors(TFTs).A TFT device based on a three-layer ZnO film prepared using precursor concentrations of 0.25,0.10,and 0.05 mol.L-1 showed a higher mobility of 0.02 cm.2V-.1s-1 compared with a TFT device(mobility of 0.013 cm.2V-.1s-1) prepared using precursor concentrations of 0.05,0.10,and 0.25 mol.L-1.Atomic force microscopy(AFM) showed that the former film with a root mean square(rms) of 3.95 nm for the roughness was smoother than the latter with a rms of 4.52 nm.We demonstrate that the roughness of the ZnO film plays an important role in the properties of the semiconductor film.A smoother film allows better contact between the source/drain and the active layer.In TFTs,charge carriers transport in the ZnO grains only near the ZnO/SiO2 insulator layer interface and the crystallinity of the initially formed layer of the film influences the performance of the TFT.X-ray diffraction(XRD) patterns showed that the initial layer formed was polycrystalline for the former film and amorphous for the latter.Our work demonstrates that the roughness of the semiconducting film and the crystallinity of the initially formed layer influence the properties of the multilayer semiconducting film.