Ultrathin In₂O₃thin-film transistors deposited from trimethylindium and ozone

Indium oxide (In₂O₃) is a promising channel material for thin-film transistors (TFTs). In this work, we develop an atomic layer deposition (ALD) process of using trimethylindium and ozone (O₃) to deposit In₂O₃films and fabricate ultrathin In₂O₃TFTs. The In₂O₃TFTs with 4 nm channel thickness show generally good switching characteristics with a highI_on/I_offof 10⁸, a high mobility (μ_FE) of 16.2cm2V-1s-1and a positive threshold voltage (V_th) of 0.48 V. Although the 4 nm In₂O₃TFTs exhibit short channel effect, it can be improved by adding an ALD Ga₂O₃capping layer to afford the bilayer In₂O₃/Ga₂O₃channel structure. The afforded In₂O₃/Ga₂O₃TFTs exhibit improved immunity to the short channel effect, with good TFT characteristics ofI_on/I_offof 10⁷,μ_FEof 9.3cm2V-1s-1, and positiveV_thof 2.23 V. Overall, the thermal budget of the entire process is only 400 °C, which is suitable for the display and CMOS back-end-of-line-compatible applications.