Improving Performance of Tin-Doped-Zinc-Oxide Thin-Film Transistors by Optimized Multi-Stacked Active-Layer Structures

TL;DR

This paper demonstrates that triple-active-layer thin-film transistors (TAL TFTs) with optimized multi-stack structures significantly improve electrical performance, making them suitable for flexible display applications with low-cost and low-temperature processing.

Contribution

The study introduces a novel triple-active-layer configuration that combines advantages of single and dual-layer TFTs, achieving superior electrical performance and stability.

Findings

High on-off current ratio of 2×10^8

Low threshold voltage of 0.52 V

Saturation mobility of 145.2 cm²/Vs

Abstract

In this paper, we investigated the performance of thin-film transistors (TFTs) with different channel configurations including single-active-layer (SAL) Sn-Zn-O (TZO), dual-active-layers (DAL) In-Sn-O (ITO)/TZO, and triple-active-layers (TAL) TZO/ITO/TZO. The TAL TFTs were found to combine the advantages of SAL TFTs (a low off-state current) and DAL TFTs (a high mobility and a low threshold voltage). The proposed TAL TFTs exhibit superior electrical performance, e.g. a high on-off state current ratio of 2*10^8, a low threshold voltage of 0.52 V, a high saturation mobility of 145.2 cm2/Vs, and a low off-state current of 3.3 pA. The surface morphology and characteristics of the ITO and TZO films were investigated and the TZO film was found to be C-axis-aligned crystalline (CAAC). A simplified resistance model was deduced to explain the high channel resistance of TAL TFTs. At last, TAL TFTs with different channel lengths were also discussed to show the stability and the uniformity of our fabrication process. Owing to its low-processing temperature, superior electrical performance, and low cost, TFTs with the proposed TAL channel configuration are highly promising for flexible displays where the use of heat-sensitive polymeric substrates is desirable.