Characterization of a sol-gel based high-k dielectric field effect transistor for cryogenic operation

A silicon on insulator field effect transistor for cryogenic operation has been fabricated using a sol-gel derived TiO2 electron beam resist as a high-k gate dielectric and characterized over a range of temperatures. The TiO2 dielectric layer allows too large a gate leakage current for good device operation at room temperature, but the leakage current is strongly suppressed at cryogenic temperatures and good transistor characteristics were observed. The temperature dependence of the gate leakage current suggests that Frenkel-Poole and trap-assisted tunneling dominates the conduction in the dielectric layer. The drain current shows peaks at certain frequencies under continuous wave microwave irradiation, which may be caused by the resonance of electrons trapped in defects at the TiO2/SiO2 interface. These resonances offer the possibility to manipulate single electrons for nonclassical information processing.