Experimental and Theoretical Analysis of Degradation in Ga₂O₃–In₂O₃–ZnO Thin-Film Transistors

Abstract

Degradation of Ga 2 O 3 -In 2 O 3 -ZnO (GIZO) thin-film transistors (TFTs), which are promising for driving circuits of next-generation displays, was studied. We evaluated degradation caused by applying gate voltage and drain voltage stress. A parallel shift of the transfer curve was observed under gate voltage stress. The amount of threshold voltage shift when applying gate and drain voltage stress was smaller than that in the case of only gate voltage stress. Joule heating caused by the drain current was observed. We reproduced this degradation of transfer curve change by device simulation. When we assumed the trap level as the density of state (DOS) model and increased two kinds of trap density, we obtained properties that show the same trends as the experimental results. We concluded that two degradation mechanisms occur under gate and drain voltage stress conditions.

Low-temperature processable amorphous In-W-O thin-film transistors with high mobility and stability

“…26 Although our IWO device was not covered with a passivation layer, excellent electrical stability was obtained. According to the previous reports, the negative V th shift under bias stress is possibly caused by the applied voltages 27,28 and/or ambient water molecules, 29 the electrical stability of the present IWO films, however, became less sensitive with increasing W concentration. This is attributed to the high oxygen bond-dissociation energy of W (720 kJ/mol).…”

Analysis of Instability Mechanism under Simultaneous Positive Gate and Drain Bias Stress in Self-Aligned Top-Gate Amorphous Indium-Zinc-Oxide Thin-Film Transistors

“…Especially, the wider W ch has higher self-heating than narrower W ch during the SPGDBS [6,8], which is consistent with Fig. 2(c).…”

“…(1), energy level of delta-DOS, but also is analogous to the extracted level by other groups [12,14]. Specifically, it is widely believed that the doubly ionized oxygen vacancy (V O 2+ ) is observed 0.1~0.3 eV from conduction-band [8,14] . Fig.…”

“…3(a) and (b) can be obvious evidences that the increase in W ch correspond with more generating donor-state because the selfheating is increased even more by increase in W ch and the increase in internal temperature of TFT will accelerate V O 2+ generation. Also, many groups have studied about the relationship between channel width and temperature [6,8].…”

“…This degradation effects were electron-hole pairs and self-heating [5]. However, in terms of investigating the degradation mechanism, there have been controversial thoughts: hole trapping into back channel by electron-hole pairs [5,6], donor-state creation at channel layer [7,8]. Such mechanisms have not been quantitatively clarified yet including which mechanism is responsible for the DV T .…”