Feasibility of Atomic Layer Deposited AlZrOx Film to Achieve High Performance and Good Stability of ZnSnO-TFT

In this paper, ZnSnO thin-film transistors (TFTs) with atomic layer deposited AlZrOx insulator of varying thicknesses are first fabricated. The electrical performance and thermal stability of ZnSnO-TFTs with different AlZrO
_x
thicknesses are characterized. The 130-nm-thick AlZrO
_x
-based TFT shows the optimized electrical properties. (Its mobility, threshold voltage, subthreshold voltage swing, and on-off ratio are 12.5 cm
²
/V·s, 0.3 V, 0.15 V/dec, and 8 × 10
⁷
, respectively.) In addition, ZnSnO-TFT with 130-nm AlZrOx film under temperature stress shows a small negative threshold voltage shift of 1.2 V. Density of states is calculated by the temperature-dependent field effect measurement. The improvement of temperature stability is attributed to the reduction of interface trap states and smooth AlZrO
_x
surface. The results are further verified by the bias stability. It indicates that using atomic layer deposited AlZrOx as a gate insulator is an effective method to achieve high performance and good stability of ZnSnO-TFT.