In this study, we investigated the effects of a post-annealing process on the performance and stability of zinc oxide thin film transistors fabricated by atomic layer deposition. After the post-annealing process in ambient air at 250 °C for 2 h, the value of the saturation mobility increased from 1.2 to 1.8 cm/Vs, the subthreshold swing decreased from 0.53 to 0.34 V/decade, and the Ion/Ioff ratio increased from 3.1 × 106 to 1.7 × 107. The positive bias stability was also enhanced after post-annealing. These results are related to the formation of another phase in which the difference of enthalpy between the semiconductor material and contact metal electrode causes the carrier concentration at the metal/semiconductor interface to increase, leading to decreased contact resistivity. Additionally, internal modification of the semiconductor/dielectric interface and/or improving the semiconductor structure, which is related to a change in the oxidation state of Zn through the incorporation of oxygen and/or hydroxide, can result in improved device performance.
Bibliographical noteFunding Information:
This work was supported by a Korea Research Foundation Grant funded by the Korean Government (MOEHRD, Basic Research Promotion Fund) (KRF- 2008-314-D00211 ).
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Metals and Alloys
- Materials Chemistry