Electrical characteristics of InGaZnO thin film transistor prepared by co-sputtering dual InGaZnO and ZnO targets

Abstract

A co-sputtering of dual InGaZnO and ZnO targets, abbreviated by ZnO co-sputtered IGZO, is used to fabricate a high performance indium gallium zinc oxide ( IGZO) thin film transistor in this work. The ZnO co-sputtered IGZO thin film exhibits a smooth (R-rms similar to 0.29 nm), featureless, and amorphous structure with high carrier density (n similar to 4.29 x 10(17) cm(-3)). The performance and stability of ZnO co-sputtered IGZO TFT has been investigated and compared with the counterparts fabricated by a single ZnO and a-IGZO target respectively. Highest linear field effect mobility of 16.1 cm(2) V-1 s(-1) with an I-on/I-off ratio of 1.04 x 10(7), saturation drain current of 3.8 mu A at 5 V, and the lowest threshold voltage of 2.0 V with subthreshold swing of 0.21 V per decade have been obtained for the ZnO co-sputtered IGZO TFT. Furthermore, the ZnO co-sputtered IGZO TFT exhibited only a threshold voltage shift (Delta V-th) of 2.75 V under negative biased illuminated stress conditions for 2500 s, whereas the IGZO and ZnO based TFTs suffered from a huge threshold voltage shift (Delta V-th > 6 V) under the same conditions. The obtained performance and stability of TFTs with ZnO co-sputtered IGZO film is very promising for low voltage display applications.