Characteristics of Low-Temperature-Annealed Zn0-TFTs

We investigated the effects of low-temperature annealing at 300 ◦C and 500 ◦C in air and N2 on the electrical characteristics of ZnO thin-film transistors (TFTs). The ZnO layers were deposited on a bottom-gate patterned Si substrate by radio-frequency (RF) sputtering at room temperature. A low-temperature oxide (LTO) served as the gate dielectric. Unannealed ZnO-TFTs were operated in the enhancement mode with a threshold voltage of 13.7 V. A field-effect mobility of 0.024 cm/Vs and an on–off current ratio of 2 × 10 were obtained. Low-temperature annealing of the ZnOTFTs in an N2 atmosphere reduced the threshold voltage of the TFTs to 12.5 V and increased the field-effect mobility to 0.047 cm/Vs and the on–off current ratio to 2 × 10.