Hongtao Cao

Oxide Materials and Devices


Ningbo Institute of Material Technology and Engineering, the Chinese Academy of Sciences , Zhongguan West Road 1219, Rm A506 315201 Ningbo, P. R. China  



Email: H_Cao@nimte.ac.cn



Hongtao Cao, Ph.D. Professor, Principle Investigator (PI). He received the Ph.D. in Materials Processing Engineering from Institute of Metal Research, Chinese Academy of Sciences in 2004. From 2004 to 2007, he was a postdoctoral research fellow at Royal Institute of Technology, Stockholm, Sweden. In 2007, he joined the faculty of the Division of Functional Materials and Nano Devices at the Ningbo Institute of Material Technology and Engineering as a professor. Dr. Cao is committed in fundamental research focusing on exploring and understanding thin films of oxide semiconductors & dielectrics, constructing oxide heterostructures or homostructures, developing new applications for oxide electronic and optoelectronic devices. Cao’s group research also includes fundamental investigations on compound oxide properties and related processing and multifunctional material integration issues. He has published more than 120 peer-reviewed journal papers with about 2700 citations to date. He has applied and authorized more than 20 Chinese patents. Up to now, he has guided and trained more than 25 postgraduate students and post-doctors.



Abstract for Presentation

 Al-induced microstructure regularization toward highmobility oxide thin-film transistors


Amorphous oxide semiconductor (AOS) has gradually replaced traditional channel materials in thin film transistors (TFTs) used in flat panel displays. However, the field effect mobility (μFE) of commercial IGZO TFTs (~10 cm2 /Vs) cannot meet the requirement for ultra-high resolution and high frame rate novel displays [1]. In this work, High μFE InSnZnO TFTs were prepared through ‘Al-induced microstructure regularization (AIMR)’ at annealing temperatures no more than 400 ℃[2]. Wellidentified nanocrystals are distributed throughout the back channel region adjacent to the Al layer, while amorphous phase still remains in the front channel region. Especially for the whole channel layer, the packing density is distinctly increased, and oxygen vacancies are largely reduced after annealing. The optimized TFT exhibits excellent performance with a remarkably boosted μFE of 53.2 cm2 /Vs, a steep sub-threshold swing of 0.18 V/dec, a threshold voltage of -0.21 V, and a marginal threshold voltage shift of -0.24 V under negative bias stress (-20 V, 3600 s). The AIMR method is also applied to some other oxide TFTs, with 2~3 times increased μFE.

[1] Z. D. Wu, H. B. Zhang, X. L. Wang, W. S. Zhou, L. Y. Liang, Y. W. Cao, and H. T. Cao, IEEE Electron Device Lett. 42(4), 529 (2021).

[2] X. L. Wang, L. Y. Liang, H. B. Zhang, H. J. Wu, W. F. Li, C. Ning, G. C. Yuan, and H. T. Cao, Appl. Phys. Lett. 119 (21) (2021)