Low‐Voltage Operation of Ring Oscillators Based on Room‐Temperature‐Deposited Amorphous Zinc‐Tin‐Oxide Channel MESFETs

Schottky diode FET logic (SDFL) ring oscillator circuits comprising metal‐semiconductor field‐effect transistors (MESFETs) based on amorphous zinc‐tin‐oxide (ZTO) n‐channels are presented. The ZTO channel layers are deposited entirely at room temperature by long‐throw magnetron sputtering. Best MESFETs exhibit on/off current ratios as high as 8.6 orders of magnitude, a sub‐threshold swing as low as 250 mV dec−1, and a maximum transconductance of 205 µS. Corresponding inverters show peakge gain magnitude (pgm) values of 83 with uncertainty levels as low as 0.5 V at an operating voltage of 5 V. Single stage delay times down to 277 ns are measured for three‐stage ring oscillators, corresponding to oscillation frequencies as high as 451 kHz. Oscillations are observed at operating voltages as low as 3 V. These results prove the feasibility of room‐temperature‐deposited, amorphous semiconducting oxide based integrated circuits with SDFL layout. The presented approach provides more efficient as well as fail‐safe device fabrication and similar oscillation frequencies at significantly lower operating voltages compared to conventional, high‐temperature processed logic circuits based on insulating gates. Ring oscillators based on amorphous zinc‐tin‐oxide (ZTO) deposited at room temperature by long‐throw magnetron sputtering are presented. Associated inverters comprise metal field‐effect transistors based on zinc‐tin‐oxide channels. Three‐stage ring oscillators exhibit oscillation frequencies as high as 451 kHz for an operating voltage of 3 V, corresponding to single stage delay times of 277 ns.