Improvement of electrical properties of ZnO TFT with NbLaO-based stacked gate dielectrics

Authors：Wang, Cong; Liu, Yurong^*; Wu, Baozi; Sui, Jian

Source：Modern Physics Letters B, 2023, 37(02).

DOI：10.1142/S0217984922502104

• Thin-film transistor
• zinc oxide
• high-k NbLao
• double-stacked gate dielectric

The double-stacked gate dielectrics (DSGD), which consisted of either NbLaO/Al2O3 or NbLaO/SiO2, were used to improve the electrical performance of zinc oxide thin-film transistor (ZnO-TFT) with single-layer NbLaO gate dielectric (SLGD). Compared to ZnO-TFT with SLGD, the ZnO-TFTs with DSGD exhibit better electrical performance, specifically for the device with the NbLaO/SiO2 DSGD, with an increase of the field-effect mobility from 5.77 cm(2)V(-1)s(-1) to 39.64 cm(2)V(-1)s(-1), an enhancement of the on/off current ratio by two orders of magnitude, a reduction of the subthreshold slope from 110 mV/decade to 70 mV/decade. The performance enhancements are attributed to a low root-mean-square surface roughness of less than 0.3 nm and a low trap-state density of less than 6 x 10(11) cm(-2) (even 2.4 x 1011 cm(-2) for the NbLaO/SiO2 DSGD) in the bulk of the channel and at the ZnO/NbLaO interface. The results imply that ZnO-TFTs with DSGD have the potential for the application of high-resolution flat panel display.