The Effect of the Charge Transfer Transition of the Tetravalent Terbium on the Photostability of Oxide Thin‐Film Transistors

Abstract The development of the next‐generation display technologies requires thin‐film transistors (TFTs) with high mobility and good negative‐bias‐illumination stress (NBIS) stability. Here, a tetravalent‐terbium‐doped indium oxide (Tb:In 2 O 3 ) semiconductor is reported, which can effectively improve the NBIS stability of the TFT while ensuring high mobility. The TFT with Tb:In 2 O 3 channel layer exhibited remarkable performance with a saturation mobility of 45.0 cm 2 V –1 s –1 (with average mobility of 38.6 cm 2 V –1 s –1 ), a turn‐on voltage ( V on ) of −1.1 V, and an on‐off current ratio of 10 8 . In addition, the Tb:In 2 O 3 TFT showed greatly improved NBIS stability with V on shift (Δ V on ) of −3.9 V (with average Δ V on of 4.0 V) under 3600 s stress with −20 V gate voltage and white light illumination (compared to Δ V on of −11.7 V for the pure In 2 O 3 TFT). Comprehensive studies reveal that the effective improvement of NBIS stability after Tb 4+ doping is mainly attributed to the wide‐band absorption of the incident blue light by the Tb4f 7 —O2p 6 to Tb4f 8 —O2p 5 charge transfer (CT) transition that has smaller overall lattice expansion/contraction and shorter relaxation time compared to V O ionization.