Depletion-type thin-film transistors with a ferroelectric insulator

We present a study of electrical characteristics of ferroelectric field-effect transistors made of PbZr${}_{\text{0.2}}$ Ti${}_{\text{0.8}}$ O${}_3$ and SnO${}_2$ :Sb thin films. Due to properly chosen semiconductor parameters, the transistor channel can be totally depleted by the ferroelectric charge displacement. The observed remnant on/off ratio of the channel current amounts to 7$\times$ 10${}^3$ . Pulse response measurements give information on data retention, device speed, and the occurrence of charge injection. The results lead to important design considerations for ferroelectric transistors.