Device characteristics of amorphous indium gallium zinc oxide thin film transistors with ammonia incorporation

The effect of ammonia gas on amorphous indium gallium zinc oxide thin film transistors is investigated. The ammonia is incorporated into the sputtered a-IGZO film during the deposition process. The results indicate that the sub-threshold swing of the NH3 incorporated TFTs is significantly improved from 2.8 to 1.0 V/decade, and the hysteresis phenomenon is also suppressed during the forward and reverse sweeping measurement. By X-ray photoelectron spectroscopy analyses, Zn–N and O–H bonds are observed in ammonia incorporated a-IGZO film. Therefore, the improvements in the electrical performance of TFTs are attributed to the passivation of dangling bonds and/or defects by ammonia.

Research highlights
► We study the effect of ammonia incorporation on a-IGZO TFTs.
► The electrical characteristics of the TFTs are improved greatly by incorporating NH3.
► The improvement can be attributed to both hydrogen and nitrogen passivation effects.
► The traps at IGZO film were passivated by forming O–H and Zn–N bonds.