Improvements of Electrical Characteristics in Poly-Si Nanowires Thin-Film Transistors with External Connection of a BiFeO3 Capacitor.

Tsung-Kuei Kang,Hone-Zern Chen,Yu-Yu Lin,Ming-Cheng Kao,Po-Jui Chang,Che-Li Lin,Han-Wen Liu

doi:10.3390/membranes11100758

Tsung-Kuei Kang, Hone-Zern Chen + Show 5 more

Open Access

https://doi.org/10.3390/membranes11100758

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Abstract

By a sol–gel method, a BiFeO3 (BFO) capacitor is fabricated and connected with the control thin film transistor (TFT). Compared with a control thin-film transistor, the proposed BFO TFT achieves 56% drive current enhancement and 7–28% subthreshold swing (SS) reduction. Moreover, the effect of the proposed BiFeO3 capacitor on IDS-VGS hysteresis in the BFO TFT is 0.1–0.2 V. Because dVint/dVGS > 1 is obtained at a wide range of VGS, it reveals that the incomplete dipole flipping is a major mechanism to obtain improved SS and a small hysteresis effect in the BFO TFT. Experimental results indicate that sol-gel BFO TFT is a potential candidate for digital application.

Highlights

Negative capacitance (NC) transistors have been widely studied, because they are considered to be one of the most promising candidates for low power applications.The negative capacitance (NC) transistor is first proposed by Salahuddin and Datta
According to the data and discussion mentioned above, it reveals that sol-gel BFO thin film transistor (TFT) is incomplete dipoles flipping, rather than complete dipoles switching in the transistor with a large IDS -VGS hysteresis [15]
The proposed BFO TFT shows improved characteristics of I ON increased by 56% and subthreshold swing (SS) reduced by 7–28%, because the sol gel BFO film show good crystallization, ferroelectric property, and a long enough NC time

Summary

Introduction

Negative capacitance (NC) transistors have been widely studied, because they are considered to be one of the most promising candidates for low power applications. BFO is a very good ferroelectric material, it is still not widely used in negative capacitance transistors. In reference [12], BFO negative capacitance transistors can achieve a very low subthreshold swing (SS) from 8.5 to 50 mV/decade, the effect of BFO capacitor on the hysteresis is about 4–5 V. As far as digital applications are concerned, more studies are needed for BFO negative capacitance transistors. Our results reveal that the incomplete dipole flipping in the BFO capacitor plays a major role to obtain a small hysteresis effect in the proposed BFO TFT device

Devices Fabrication

Results and Discussion

Conclusions