Multiple ink-jet printed zinc tin oxide layers with improved TFT performance

Abstract

In the last two decades, metal-oxides, like zinc tin oxide (ZTO), are widely studied semiconductors for transistor applications. This study presents a simple, non-toxic, stable, and cost efficient precursor route for ZTO deposition by ink-jet printing. Such fabricated thin films are composed of an amorphous phase with embedded ZnO nanocrystals. The saturation mobility of ink-jet printed transistors increases from 0.05 cm2 V−1 s−1 for a single semiconducting layer to 7.8 cm2 V−1 s−1 for a transistor composed of 8 layers. This constitutes the highest saturation mobility of an ink-jet printed ZTO transistor reported so far. The devices exhibit large output currents (up to 38.7 mA) and high on/off ratios (exceeding 108). The large improvement in transistor performance with the number of layers is ascribed to an improved degree of substrate coverage confirmed by AFM investigations.