A unified explicit charge-based capacitance model for metal oxide thin-film transistors

•The model offers a unified and explicit expression across all working regions of the MO TFTs.•The model takes into account the non-reciprocity of capacitance, ensuring charge conservation at all ports.•Based on the fabricated IZO TFTs, comprehensive and sufficient experimental data on capacitance was tested in the article. A unified and complete capacitance model of metal oxide thin-film transistors (MO TFTs) based on three-terminal charges is proposed in this paper. The analytical expression of the three-terminal charges is obtained with the effective charge density approach and the Ward-Dutton charge partitioning approach. By considering the non-reciprocal capacitance between any two terminals, the complete capacitance model of the MO TFTs is proposed with an accurate description. The proposed model has a uniform and analytical capacitance expression over the full working regions with a specific physical meaning based on the surface potential solution. Furthermore, the sufficient capacitance experimental data of the fabricated IZO-TFT are presented to verify the proposed model. It is shown that there is a good agreement between the experimental data and the proposed model in a wide range of working regions.