Enhanced mobility and bias stability of SnO2 thin-film transistors enabled by Ga2O3 passivation-induced two-dimensional electron gas

This study presents a method to achieve both high performance and electrical stability in SnO 2 thin-film transistors (TFTs) fabricated by a sol–gel process. Sol–gel–processed Ga 2 O 3 passivation layers are introduced onto the SnO 2 active channel layers to address bias instabilities. The Ga 2 O 3 films passivate the back channel by compensating dangling bonds and isolating the channel from H 2 O and O 2 , which improves bias stability. Structural, optical, chemical, and device-level properties were systematically analyzed. When Ga 2 O 3 is deposited on SnO 2 , electrons redistribute to maintain thermal equilibrium and become confined in the potential well of SnO 2 , forming a quasi two-dimensional electron gas that increases the free carrier concentration. This effect results in a 1.5-fold enhancement in field-effect mobility (from ∼10 cm 2 /Vs to ∼15 cm 2 /Vs) together with improved bias stability. The proposed SnO 2 –Ga 2 O 3 passivation method offers a promising route toward bias-stable, high-performance metal oxide films for applications in TFTs, solar cells, transparent conducting electrodes, and resistive random-access memory (ReRAM). • Sol-gel processed SnO 2 /G 2 O 3 hetero structure were introduced for metal oxide thin film transistors. • The deposited Ga 2 O 3 films effectively passivate the back channel of the TFTs, leading to bias stability of TFTs. • A-quasi two-dimensional electron gas was formed in the potential well of SnO 2 due to lower work function of Ga 2 O 3 . • The increased carrier concentration results in enhancement in field effect mobility simultaneously.