Enhanced Electrical Characteristics and Stability via Simultaneous Ultraviolet and Thermal Treatment of Passivated Amorphous In–Ga–Zn–O Thin-Film Transistors

Abstract

We developed a method to improve the electrical performance and stability of passivated amorphous In-Ga-Zn-O thin-film transistors by simultaneous ultraviolet and thermal (SUT) treatment. SUT treatment was carried out on fully fabricated thin-film transistors, including deposited source/drain and passivation layers. Ultraviolet (UV) irradiation disassociated weak and diatomic chemical bonds and generated defects, and simultaneous thermal annealing rearranged the defects. The SUT treatment promoted densification and condensation of the channel layer by decreasing the concentration of oxygen-vacancy-related defects and increasing the concentration of metal-oxide bonds. The SUT-treated devices exhibited improved electrical properties compared to nontreated devices: field-effect mobility increased from 5.46 to 13.36 V·s, sub-threshold swing decreased from 0.49 to 0.32 V/decade, and threshold voltage shift (for positive bias temperature stress) was reduced from 5.1 to 1.9 V.

The self-activated radical doping effects on the catalyzed surface of amorphous metal oxide films

“…This means that OH* has preferentially bonded with V 0 and metal cation defects in a-IGZO films for the increase in Zn-O (Zn 2+ ) and decrease in Zn + . We additionally investigated the location of the Fermi energy level of SRD a-IGZO films in valence band offsets derived from XPS data to verify the reason for the improvement of μ FET despite the decreasing V 0 concentration 31,32 . For the SRD a-IGZO films, the Fermi level was located relatively close to the conduction band, as shown in Figure S5.…”

P-5: A Simple Dipping Method to Improve Positive Bias Stress Stability of In-Ga-Zn-O Thin-Film Transistors using Hydrogen Peroxide

“…These results are well consistent with electrical characteristics. (2) the adsorption of oxygen or water molecules at the back channel surface [9]. From these result, we can confirm that the hydrogen peroxide treatment increases metaloxide bond on the back channel, which prevents the interaction between back channel and oxygen in ambient atmosphere effectively.…”

Reduction of activation temperature at 150°C for IGZO films with improved electrical performance via UV-thermal treatment

“…Thus, the improvement of the V th shift for the U-Tactivated device is attributed to the following: (1) the reduction of the negative charges trapped between the channel and the gate insulator and (2) the alleviation of the adsorption effects on the backchannel regions. Two factors could be regarded as the reasons for the improvement of the film quality with lower defect sites related to oxygen vacancies, and higher chemical bonds [11][12]. In the mechanism of U-T activation, our UV irradiation Table 1.…”