Analysis of the Ambipolar Conduction of Tin Monoxide Thin-Film Transistors with Indium Tin Oxide Electrodes

Abstract

This study investigates the hole and electron conduction properties of thin-film transistors (TFTs) with a tin monoxide (SnO) channel and indium tin oxide (ITO) source/drain (S/D) electrodes, considering the adoption to three-dimensional (3D) NAND Flash. Compared to SnO TFTs with gold (Au) S/D electrodes, significant enhancement of electron conduction was observed when adopting ITO S/D electrodes. The ITO electrodes decreased the Schottky barrier height for electron injection, enhancing electron conduction and consequently inducing ambipolar conduction behavior. The ambipolar SnO TFT exhibited coexisting electron and hole channels, which induced a transition from normal to abnormal conduction properties. These transitioning conduction characteristics were analyzed, and a method to extract saturation mobility in ambipolar TFTs considering the electron-hole (e-h) recombination effect was proposed. Furthermore, bias-stress stability tests were conducted to examine the effect of the coexisting electron and hole channels on the carrier-trapping properties. This analysis provides valuable insights into the electrical characteristics of ambipolar TFTs, considering the coexisting electron and hole channels.