We report undoped ZnO films deposited at low temperature (200°C) using plasma-enhanced chemical vapor deposition (PECVD). ZnO thin-film transistors (TFTs) fabricated using ZnO and Al 2O 3 deposited in situ by PECVD with moderate gate leakage show a field-effect mobility of 10 cm 2/V s, threshold voltage of 7.5 V, subthreshold slope <1 V/dec, and current on/off ratios >10 4. Inverter circuits fabricated using these ZnO TFTs show peak gain magnitude (dV out/dV in) ~5. These devices appear to be strongly limited by interface states and reducing the gate leakage results in TFTs with lower mobility. For example, ZnO TFTs fabricated with low-leakage Al 2O 3 have mobility near 0.05 cm 2/V s, and five-stage ring-oscillator integrated circuits fabricated using these TFTs have a 1.2 kHz oscillation frequency at 60 V, likely limited by interface states.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering
- Materials Chemistry