A novel process is developed in which thin film transistors (TFTs) comprising one binary oxide for all transistor layers (gate, source/drain, semiconductor channel, and dielectric) are fabricated in a single deposition system at low temperature. By simply changing the flow ratio of two chemical precursors, C8 H24 HfN4 and (C2 H5 )2 Zn, in an atomic layer deposition system, the electronic properties of the binary oxide (Hf x Zn1- x O2- δ or HZO) are tuned from conducting, to semiconducting, to insulating. Furthermore, by carefully optimizing the properties of the various transistor HZO layers, all-HZO thin film transistors are achieved with excellent performance on both glass and plastic substrates. Specifically, the optimized all-HZO TFTs show a saturation mobility of ≈17.9 cm2 V-1 s-1 , low subthreshold swing of ≈480 mV dec-1 , high Ion /Ioff ratio of >109 , and excellent gate bias stability at elevated temperatures. In addition, all-HZO inverters with high DC voltage gain (≈470), and all-HZO ring oscillators with low stage delay (≈408 ns) and high oscillation frequency of 245 kHz are demonstrated. This approach presents a novel, simple, high performance, and cost-effective process for the fabrication of indium-free transparent electronics.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: Research reported in this publication was supported by the King Abdullah University of Science and Technology (KAUST). The authors would like to thank Dr. Zhenwei Wang for his help for preparing photo masks. The authors also would like to thank core laboratory staff, especially Dr. Mohamed Nejib Hedhili, Sergei Lopatin, and Nini Wei for their supports. F.H.A. and M.K.H. contributed equally to this work.