Metal Based Nonvolatile Field-Effect Transistors

The reduction of metals from their oxides through solid electrochemical reactions usually requires a high temperature above 800 degrees C and a specially designed electrochemical structure. It is demonstrated that, in a simple field-effect transistor (FET) structure, the redox reaction between Co metal and CoOx is reversible under a small electric field and can be achieved at a moderate temperature below 200 degrees C. The FETs functioning through the reversible redox reaction show nonvolatile behavior and a high on/off ratio of about 10(5). Moreover, the FETs show a threshold resistance switching behavior at high resistance states, but with opposite switching directions compared to normal metal/oxide/metal structures. The electric field induced metal-oxide transition may also be used for other energy storage applications.