MRS Proceedings


High Mobility ZnO thin film transistors using the novel deposition of high-k dielectrics

2010 MRS Fall Meeting.

D. K. Ngwashia1, R. B. M. Crossa1, S. Paula1, Andrian P. Milanova2 and Anjana Devia2

a1 Emerging Technologies Research Centre, De Montfort University Leicester LE1 9BH, UK

a2 Inorganic Materials Chemistry Group, Inorganic Chemistry II, Ruhr-University Bochum, 44801 Bochum, Germany


In order to investigate the performance of ZnO-based thin film transistors (ZnO-TFTs), we fabricate devices using amorphous hafnium dioxide (HfO2) high-k dielectrics. Sputtered ZnO was used as the active channel layer, and aluminium source/drain electrodes were deposited by thermal evaporation, and the HfO2 high-k dielectrics are deposited by metal-organic chemical vapour deposition (MOCVD). The ZnO-TFTs with high-k HfO2 gate insulators exhibit good performance metrics and effective channel mobility which is appreciably higher in comparison to SiO2-based ZnO TFTs fabricated under similar conditions. The average channel mobility, turn-on voltage, on-off current ratio and subthreshold swing of the high-k TFTs are 31.2 cm2V-1s-1, -4.7 V, ~103, and 2.4 V/dec respectively. We compared the characteristics of a typical device consisting of HfO2 to those of a device consisting of thermally grown SiO2 to examine their potential for use as high-k dielectrics in future TFT devices.

Key Words:

  • thin film;
  • devices;
  • semiconducting
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