Study on improving performance of In 2 O 3 /ZnO heterojunction thin-film transistors fabricated by atomic layer deposition process

Abstract To address the incompatibility of high-temperature processes for traditional heterojunction thin-film transistors (TFTs) with flexible substrates and the difficulty in balancing field-effect mobility ( μ FE ) and subthreshold swing (SS), this study fabricated In 2 O 3 /ZnO bilayer and In 2 O 3 /Ga 2 O 3 /ZnO triple-layer heterojunction TFTs via atomic layer deposition using a low-temperature process (≤120 °C). By adjusting the ZnO layer thickness (10–25 nm), the optimal performance of the In 2 O 3 /ZnO bilayer device was achieved: μ FE of 47 cm 2 V −1 s −1 , SS of 65.56 mV decade −1 , on/off ratio >10 9 , and bias stability with threshold voltage shift ( ∆ V TH ) < ±0.2 V. After introducing a Ga 2 O 3 intermediate layer, the In 2 O 3 /Ga 2 O 3 /ZnO triple-layer device exhibited a μ FE of 77.14 cm 2 V −1 s −1 while the SS still remained at an excellent level of 72 mV decade −1 , with stability meeting flexible application requirements. This low-thermal-budget heterojunction design provides a new solution for device integration in flexible displays and 3D memory.