Feasibility of Atomic Layer Deposited AlZrOxFilm 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 AlZrOxthicknesses are characterized. The 130-nm-thick AlZrOx-based TFT shows the optimized electrical properties. (Its mobility, threshold voltage, subthreshold voltage swing, and on-off ratio are 12.5 cm2/V·s, 0.3 V, 0.15 V/dec, and 8 × 107, 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 AlZrOxsurface. 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.