Influence of Weight Ratio of Poly(4-vinylphenol) Insulator on Electronic Properties of InGaZnO Thin-Film Transistor

C J Chiu,S P Chang,S J Chang,Z W Pei

doi:10.1155/2012/698123

C J Chiu, S P Chang + Show 2 more

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https://doi.org/10.1155/2012/698123

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Abstract

Spin-coated organic PVP layers were used as dielectric layers in a-IGZO TFTs. Weight ratios of 20 : 1, 10 : 1, and 5 : 1 for PVP and PMF, a cross-linking agent, were used. The a-IGZO TFTs with the PVP : PMF ratio of 20 : 1 showed a large hysteresis in theI-Vcurve andC-Vcurve, the hysteresis increases with the increase of hydroxyl groups and also deteriorated the gate leakage current. In contrast, the devices with the PVP : PMF ratio of 5 : 1 dielectric displayed only small hysteresis. According to our experimental results, preventing the possible diffusion of hydroxyl-contained species in polymeric dielectrics is a very important factor in improving the electrical properties of high-performance a-IGZO TFT devices.

Highlights

Hydrogenated amorphous silicon (a-Si:H) was widely used for the fabrication of the channel layer of thin-film transistors (TFTs); some of the inherent characteristics of these films, such as lower mobility (∼1 cm2/Vs) and poor transparency, have limited their applications
Fourier-transform infrared (FTIR) spectroscopy is a powerful technology for studying intermolecular interactions in polymers
In the PVP : poly(melamine-coformaldehyde) methylated (PMF) FTIR spectrum, the band corresponding to the C–N stretching vibration at 1019 cm−1 [12] and the strong band corresponding to the C=H stretching vibration at 1380 cm−1 and 1447 cm−1 which are assigned to the inner face bending vibration of hydroxyl group [13]

Summary

Introduction

Hydrogenated amorphous silicon (a-Si:H) was widely used for the fabrication of the channel layer of thin-film transistors (TFTs); some of the inherent characteristics of these films, such as lower mobility (∼1 cm2/Vs) and poor transparency, have limited their applications. Poly(4-vinylphenol) (PVP), an organic dielectric, has been widely utilized in organic thin-film transistors (OTFTs) because it is inexpensive and can be used for the fabrication of films having a large area, making it useful for applications to flexible electronics. We can obtain lower roughness and high performance electric properties of TFTs. Bang et al [10] reported they compared the characteristics of bottom-gate ZnO-thin film transistors using poly-4-vinylphenol (PVP) and PVP/Al2O3 dielectrics. Several groups have investigated the hysteresis effect with different weight ratios of polymer gate dielectric layer [12, 13] Such studies have been reported to clarify the relationship between the weight ratio of the constituents of the PVP insulator and the electric properties of the device. In aIGZO TFT devices were confirmed to be strongly related to the hydroxyl bonds existing inside of polymeric dielectrics

Experimental Details

Results and Discussion

Conclusion