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The influence of the SiO2 gate insulator thickness to the performance and Bias-voltage stress stability of ZnO thin-film-transistors

F. ZHOU1,* , H. P. LIN1, J. LI1, L. ZHANG1, X.W. ZHANG2, D. B. YU1, X. Y. JIANG1, Z.L. ZHANG1,3, J.H. ZHANG3

Affiliation

  1. School of Materials Science and Engineering, Shanghai University, Shanghai 200072,China
  2. Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004, China
  3. Key Laboratory of Advanced Display and System Application, Ministry of Education, Shanghai University, 200072, China

Abstract

Top-contact thin film transistors using radio frequency sputtering ZnO and SiO2 films as channel layer and gate insulator are fabricated in this work. The performance of ZnO-TFTs with different thickness SiO2 dielectrics are compared. The experiment results show that the SiO2 dielectric thickness plays an important role on enhancing both the field effect mobility and bias stability of the devices. The device with 150 nm thick SiO2 insulator has much better performances: its mobility reaches 6.1cm2 /V.S, subthreshold swing is 1.6 V/Dec, bias-voltage stress induced ∆Vth is 3V.. Comparison of 150 nm thickness with 200 nm thickness and 300 nm thickness SiO2 insulator based devices shows that the field effect mobility improved by 250% and 150% and sub-threshold swing decreased by 60% and 25%, respectively, while bias-voltage stress instability reduced from 6V and 9.4V to 3V. The improved performance can be attributed to that the thinner insulator has larger capacitance and contains smaller amounts of total trap centers compared with the thicker dielectrics..

Keywords

ZnO-TFT, Oxygen partial pressure, Interface properties, RF magnetron sputtering.

Submitted at: Jan. 10, 2011
Accepted at: July 25, 2011

Citation

F. ZHOU, H. P. LIN, J. LI, L. ZHANG, X.W. ZHANG, D. B. YU, X. Y. JIANG, Z.L. ZHANG, J.H. ZHANG, The influence of the SiO2 gate insulator thickness to the performance and Bias-voltage stress stability of ZnO thin-film-transistors, Journal of Optoelectronics and Advanced Materials Vol. 13, Iss. 7, pp. 797-801 (2011)