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

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: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 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:In2O3 TFT showed greatly improved NBIS stability with V-on shift (Delta V-on) of -3.9 V (with average Delta V-on of 4.0 V) under 3600 s stress with -20 V gate voltage and white light illumination (compared to Delta V-on 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)-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.