High-Frequency ZnO Thin-Film Transistors on Si Substrates

Record microwave frequency performance was achieved with nanocrystalline ZnO thin-film transistors fabricated on Si substrates. Devices with 1.2-mum gate lengths and Au-based gate metals had current and power gain cutoff frequencies of f_T = 2.45 GHz and f_max = 7.45 GHz, respectively. Same devices had drain-current on/off ratios of 5 times10¹⁰ exhibited no hysteresis effects and could be operated at a current density of 348 mA/mm. The microwave performances of devices with 1.2- and 2.1- mum gate lengths and 50- and 100-mum gate widths were compared.