Low leakage current—stacked MgO/Bi_1.5Zn_1.0Nb_1.5O₇ gate insulator— for low voltage ZnO thin film transistors

The authors report on the role of MgO capping layers in notably reducing leakage currents and improving mobility in ZnO thin film transistors (TFTs) utilizing compatible high-k Bi_1.5Zn_1.0Nb_1.5O₇ (BZN) gate insulators. All room temperature processed ZnO based TFTs with stacked MgO/BZN gate insulator exhibited a much enhanced field effect mobility of 5.4 cm²/V s with excellent saturation characteristics as compared to that (μ_FE=1.13 cm²/V s) of ZnO based TFTs with BZN gate insulator. This work demonstrates the suitability of MgO/BZN stacked gate insulators in the fabrication of low voltage ZnO based TFTs on plastic substrates.