Lee Hyeonju, Zhang Xue, Hwang Jaeeun, Park Jaehoon
Department of Electronic Engineering, Hallym University, Chuncheon 24252, Korea.
Department of Advanced Materials Engineering for Information & Electronics, Kyung Hee University, Yongin 17104, Korea.
Materials (Basel). 2016 Oct 19;9(10):851. doi: 10.3390/ma9100851.
We report on the morphological influence of solution-processed zinc oxide (ZnO) semiconductor films on the electrical characteristics of ZnO thin-film transistors (TFTs). Different film morphologies were produced by controlling the spin-coating condition of a precursor solution, and the ZnO films were analyzed using atomic force microscopy, X-ray diffraction, X-ray photoemission spectroscopy, and Hall measurement. It is shown that ZnO TFTs have a superior performance in terms of the threshold voltage and field-effect mobility, when ZnO crystallites are more densely packed in the film. This is attributed to lower electrical resistivity and higher Hall mobility in a densely packed ZnO film. In the results of consecutive TFT operations, a positive shift in the threshold voltage occurred irrespective of the film morphology, but the morphological influence on the variation in the field-effect mobility was evident. The field-effect mobility in TFTs having a densely packed ZnO film increased continuously during consecutive TFT operations, which is in contrast to the mobility decrease observed in the less packed case. An analysis of the field-effect conductivities ascribes these results to the difference in energetic traps, which originate from structural defects in the ZnO films. Consequently, the morphological influence of solution-processed ZnO films on the TFT performance can be understood through the packing property of ZnO crystallites.
我们报道了溶液法制备的氧化锌（ZnO）半导体薄膜对ZnO薄膜晶体管（TFT）电学特性的形态学影响。通过控制前驱体溶液的旋涂条件制备了不同的薄膜形态，并使用原子力显微镜、X射线衍射、X射线光电子能谱和霍尔测量对ZnO薄膜进行了分析。结果表明，当ZnO微晶在薄膜中更紧密堆积时，ZnO TFT在阈值电压和场效应迁移率方面具有优异的性能。这归因于紧密堆积的ZnO薄膜中较低的电阻率和较高的霍尔迁移率。在连续的TFT操作结果中，无论薄膜形态如何，阈值电压都会出现正向偏移，但形态对场效应迁移率变化的影响是明显的。具有紧密堆积ZnO薄膜的TFT中的场效应迁移率在连续的TFT操作过程中持续增加，这与在堆积较少情况下观察到的迁移率降低形成对比。对场效应电导率的分析将这些结果归因于能量陷阱的差异，这些陷阱源于ZnO薄膜中的结构缺陷。因此，通过ZnO微晶的堆积特性可以理解溶液法制备的ZnO薄膜对TFT性能的形态学影响。
