AZO Thin Film Transistor Performance Enhancement by Capping an Aluminum Layer

Coplanar bottom-gate aluminum-zinc-oxide (AZO) thin film transistors (TFTs) with aluminum (Al) capping layers were fabricated in this work. The influences of the Al capping layer thickness and the post-annealing condition on the performance of the AZO-TFTs were investigated. Results show that the performance of the AZO-TFTs are enhanced significantly by introducing the Al capping layer on back channel, with saturation mobility increasing dramatically from 0.128 to 12.6 cm 2 /V · s. The enhancement is ascribed to the diffusion of Al atoms into the AZO thin film and thus induced crystallization improvement.