Anomalous capacitance change in low-temperature grown ZnO thin-film transistors
Department of Electrical and Computer Engineering, Ajou University, Suwon, 443-749, Korea
Corresponding author: email@example.com
Revised: 9 May 2010
Accepted: 23 July 2010
Published online: 17 September 2010
We studied capacitance-voltage characteristics of ZnO thin-film transistors (TFT's), grown by metalorganic chemical vapor deposition (MOCVD). We compared two ZnO TFT's: one grown at 450 °C and the other at 350 °C. ZnO grown at 450 °C showed smooth capacitance profile with electron density of 1.5×1020 cm-3. In contrast, ZnO grown at 350 °C showed a capacitance jump when gate voltage was changed to negative voltages. Current-voltage characteristics measured in the two samples did not show much difference. We explain that the capacitance jump is related to p-type ZnO layer formed at the SiO2 interface. Current-voltage and capacitance-voltage data support that our ZnO films have anisotropic conductivity.
© EDP Sciences, 2010