Ultrathin In 2 O 3 thin-film transistors deposited from trimethylindium and ozone.

Indium oxide (In 2 O 3 ) 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 (O 3 ) to deposit In 2 O 3 films and fabricate ultrathin In 2 O 3 TFTs. The In 2 O 3 TFTs with 4 nm channel thickness show generally good switching characteristics with a high I on / I off of 10 8 , a high mobility ( μ FE ) of 16.2cm2V-1s-1and a positive threshold voltage ( V th ) of 0.48 V. Although the 4 nm In 2 O 3 TFTs exhibit short channel effect, it can be improved by adding an ALD Ga 2 O 3 capping layer to afford the bilayer In 2 O 3 /Ga 2 O 3 channel structure. The afforded In 2 O 3 /Ga 2 O 3 TFTs exhibit improved immunity to the short channel effect, with good TFT characteristics of I on / I off of 10 7 , μ FE of 9.3cm2V-1s-1, and positive V th of 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.