Effects of hydrogen plasma treatment on the electrical performances and reliability of InGaZnO thin-film transistors

Abstract

In this work, we have investigated the effects of hydrogen (H) plasma treatment on the electrical performances and reliability of amorphous InGaZnO (a-IGZO) thin film transistors (TFTs). By optimizing the H plasma treatment time, the a-IGZO TFT with H plasma treatment time of 1 min exhibits excellent electrical performances and reliability, such as high field-effect mobility (μFE) of 26.5 cm2/V s and small threshold voltage shifts (ΔVth) value of 2.5 V and −2.3 V under positive gate bias stress (PBS) and negative gate bias stress (NBS) measurements without any passivation layers. The increased performance relies that the H plasma treatment not only could increase the carrier concentration (Ne) but also reduce the surface defects of channel layer and interface trap density of a-IGZO TFTs. The X-ray photo-electron spectroscopy measurement reveals that the H treatment passivated the oxygen vacancy (VO) defects and formed center-bonded complex states (HO or VO-H) in the a-IGZO films, which act as a shallow donor in a-IGZO films. Therefore, the high performances and excellent reliability of a-IGZO TFTs is suggesting that H is a very promising treatment for TFTs to be used for flexible thin film electronic applications.