Thermal\nDehydrogenation\nImpact on Positive Bias Stability\nof Amorphous InSnZnO Thin-Film Transistors

Abstract

Recently, the growing demand for\namorphous oxide semiconductor\nthin-film transistors (AOS TFTs) with high mobility and good stability\nto implement ultrahigh-resolution displays has made tracking the role\nof hydrogen in oxide semiconductor films increasingly important. Hydrogen\nis an essential element that contributes significantly to the field\neffect mobility and bias stability characteristics of AOS TFTs. However,\nbecause hydrogen is the lightest atom and has high reactivity to metal\nand oxide materials, elucidating its impact on AOS thin films has\nbeen challenging. Therefore, in this study, we propose controlling\nthe hydrogen quantities in amorphous InSnZnO (a-ITZO) thin films through\nthermal dehydrogenation to precisely reveal the hydrogen influences\non the electrical characteristics of a-ITZO TFTs. The as-deposited\ndevice containing 15.69 × 10¹⁵ atoms/cm² of hydrogen exhibited a relatively low saturation mobility of 18.1\ncm²/V·s and poor positive bias stress stability. However,\ndepending on the extent of thermal dehydrogenation, not only did the\nhydrogen quantity and interface defect density (<i>D</i>_IT) decrease but also the conductivity and surface energy\nincreased due to the rise in oxygen vacancies and hydroxyl groups\nin a-ITZO thin films. As a result, the a-ITZO TFT with a hydrogen\namount of 4.828 × 10¹⁵ atoms/cm² showed\nthat the saturation mobility improved up to 36.8 cm²/V·s,\nand positive bias stress stability was remarkably enhanced. Hence,\nwe report the ability to manage the hydrogen quantity with thermal\ndehydrogenation and demonstrate that high-performance a-ITZO TFTs\ncan be realized when an appropriate hydrogen concentration is achieved.