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

Abstract

AbstractThe 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:In2O3) semiconductor is reported, which can effectively improve the NBIS stability of the TFT while ensuring high mobility. The TFT with Tb:In2O3 channel layer exhibited remarkable performance with a saturation mobility of 45.0 cm2 V–1 s–1 (with average mobility of 38.6 cm2 V–1 s–1), a turn‐on voltage (Von) of −1.1 V, and an on‐off current ratio of 108. In addition, the Tb:In2O3 TFT showed greatly improved NBIS stability with Von shift (ΔVon) of −3.9 V (with average ΔVon of 4.0 V) under 3600 s stress with −20 V gate voltage and white light illumination (compared to ΔVon of −11.7 V for the pure In2O3 TFT). Comprehensive studies reveal that the effective improvement of NBIS stability after Tb4+ doping is mainly attributed to the wide‐band absorption of the incident blue light by the Tb4f 7—O2p6 to Tb4f 8—O2p5 charge transfer (CT) transition that has smaller overall lattice expansion/contraction and shorter relaxation time compared to VO ionization.