Optimization of Solution-Processed ITZO/IGZO Dual-Active-Layer Thin-Film Transistors

Abstract

We successfully fabricated dual-active-layer (DAL) thin-film transistors (TFTs) via a solution process with an active back InGaZnO (IGZO) layer and an active front InSnZnO (ITZO) layer. Our optimized DAL TFT displayed optimal performance characteristics with a saturation mobility (mu(sat)) of 11.5 cm(2)/V . s, a steep subthreshold swing of 0.36 V/dec, and a high on/off ratio exceeding 10(7). This mobility represents an order of magnitude increase when compared to a single active layer (SAL) TFT with an ITZO active layer. Furthermore, the devices exhibited an improved positive bias stress (PBS) of Delta V-TH + 2.6 V under a positive bias stress of 10 V. In order to determine which factors resulted in the observed enhanced electrical performance, we analyzed the role of the front and back channels while varying the molarity of the active layer. Changes in the front and back channels influenced the current path, the V-TH and the off current.