Abstract
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.
Highlights
Over the last decade, oxide semiconductors have attracted considerable attention both in academia and industry owing to their high electrical conductivity and excellent optical transparency
These results prove that charge-trapping sites at the SiO2 solution-processed zinc oxide (ZnO) film, and their energetic depth is dominantly determined by the packing dielectric/ZnO semiconductor interface are created owing to structural defects, such as pinholes and densityvoids, of ZnO
We investigated the morphological influence of solution-processed ZnO semiconductor films on the electrical characteristics of ZnO thin-film transistors (TFTs)
Summary
Oxide semiconductors have attracted considerable attention both in academia and industry owing to their high electrical conductivity and excellent optical transparency. It has been reported that the electrical conductivity of these materials can be increased up to 103 S/cm and the optical transparency in the visible-light region is more than 85% [1,2]. These inherent features of oxide semiconductors are highly beneficial for their use in electronics and optoelectronics. High-resolution organic light-emitting diode displays that employ an oxide TFT backplane are an example of recent advancement in this technology [6,7]. It is envisioned that solution-processable oxide materials and solution-based manufacturing processes will pave the way for next-generation flexible and disposable electronics
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