Comparison of ZnO-Based JFET, MESFET, and MISFET

We compare key properties of zinc oxide (ZnO)-based junction field-effect transistors (JFETs), metal-semiconductor field-effect transistors (MESFETs), and metal-insulator-semiconductor field-effect transistors (MISFETs) prepared from a common ZnO:Mg thin film. The JFETs are fabricated with a ZnCo ₂ O ₄ -gate, the MESFETs with reactively sputtered Pt-gate and the MISFETs with WO ₃ as gate insulator. The three FET types are compared with regarding dc characteristics, frequency dependence, and stability at temperatures up to 150°C. All devices can be switched within a similar gate voltage range of less than 3 V, making a direct comparison of the device characteristics possible. Measurements above room temperature show a common shift of the transfer curves to higher gate voltages, which seems to be a distinguishing property of ZnO compared with other semiconductors. All electric measurements show major differences between the devices, which can be attributed to the different gate structures.