Insulator-to-semiconductor conversion of solution-processed ultra-wide bandgap amorphous gallium oxide via hydrogen annealing

Developing semiconducting solution-processed ultra-wide bandgap (UWB) amorphous oxide semiconductor (AOS) is an emerging area of research interest. However, obtaining electrical conduction on it is quite challenging. Here, we demonstrate the insulator-to-semiconductor conversion of solution-processed a-Ga2Ox (Eg~4.8 eV) through hydrogen annealing. The successful conversion was reflected by the switching thin-film transistor (TFT) with μsat of 10-2 cm2/Vs. We showed that H incorporated after hydrogen annealing acts as a shallow donor which increased the carrier concentration and shifted the EF closer to the CBM.

An Empirical Modeling of Gate Voltage-Dependent Behaviors of Amorphous Oxide Semiconductor Thin-Film Transistors including Consideration of Contact Resistance and Disorder Effects at Room Temperature

In this paper, we present an empirical modeling procedure to capture gate bias dependency of amorphous oxide semiconductor (AOS) thin-film transistors (TFTs) while considering contact resistance and disorder effects at room temperature. From the measured transfer characteristics of a pair of TFTs where the channel layer is an amorphous In-Ga-Zn-O (IGZO) AOS, the gate voltage-dependent contact resistance is retrieved with a respective expression derived from the current–voltage relation, which follows a power law as a function of a gate voltage. This additionally allows the accurate extraction of intrinsic channel conductance, in which a disorder effect in the IGZO channel layer is embedded. From the intrinsic channel conductance, the characteristic energy of the band tail states, which represents the degree of channel disorder, can be deduced using the proposed modeling. Finally, the obtained results are also useful for development of an accurate compact TFT model, for which a gate bias-dependent contact resistance and disorder effects are essential.

Author Correction: Realization of tunable artificial synapse and memory based on amorphous oxide semiconductor transistor

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The Investigation of Indium-Free Amorphous Zn-Al-Sn-O Thin Film Transistor Prepared by Magnetron Sputtering

The indium-free amorphous oxide semiconductor thin film transistor (AOS-TFT) with aluminum (Al) electrodes shows broad application prospects in new-generation display technologies, such as ultra-high definition large-screen display, OLED display and 3D display. In this work, the thin film transistor (TFT) with a zinc-aluminum-tin-oxide (ZATO) semiconductor as the active layer and an Al electrodes as the source and drain (S/D) was investigated. The optical, electrical and semiconductive properties of the ZATO films were evaluated by atomic force microscopy (AFM), ultraviolet–visible spectrophotometry and microwave photoconductivity decay (μ-PCD), respectively. The result shows that the film is smooth and transparent and has low localized states and defects at a moderate oxygen concentration (~5%) and a low sputtering gas pressure (~3 mTorr). After the analysis of the transfer and output characteristics, it can be concluded that the device exhibits an optimal performance at the 623 K annealing temperature with an Ion/Ioff ratio of 5.5 × 107, an SS value of 0.15 V/decade and a saturation mobility (μsat) of 3.73 cm2·V−1·s−1. The ZATO TFT at the 623 K annealing has a −8.01 V negative shift under the −20 V NBS and a 2.66 V positive shift under the 20 V PBS.