RF Characteristics of Room-Temperature-Deposited, Small Gate Dimension Indium Zinc Oxide TFTs

Depletion-mode indium zinc oxide channel thin film transistors (TFTs) with gate dimension of and drain-to-source distance of were fabricated on glass substrates using radio frequency magnetron sputtering deposition at room temperature. Plasma-enhanced chemical vapor deposited was used as the gate insulator. The threshold voltage was around . Saturation current density at zero gate bias voltage was 2 mA/mm, and a maximum transconductance of 7.5 mS/mm was obtained at . The drain current on-to-off ratio was . The maximum field effect mobility measured in the saturation region was . A unity current gain cutoff frequency, , and maximum frequency of oscillation, of 180 and 155 MHz, respectively, were obtained. The equivalent device parameters were extracted by fitting the measured parameters to obtain the intrinsic transconductance, drain resistance, drain-source resistance, transit time, and gate-drain and gate-source capacitance.