Composition-dependent oxygen vacancy formation in multicomponent wide-band-gap oxides

Abstract

The formation and distribution of oxygen vacancy in layered multicomponent InAM O4 oxides with A 3+ =Al or Ga, and M 2+ =Ca or Zn, and in the corresponding binary oxide constituents is investigated using first-principles density functional calculations. Comparing the calculated formation energies of the oxygen defect at six different site locations within the structurally and chemically distinct layers of InAM O4 oxides, we find that the vacancy distribution is significantly affected not only by the strength of the metal-oxygen bonding, but also by the cation's ability to adjust to anisotropic oxygen environment created by the vacancy. In particular, the tendency of Zn, Ga, and Al atoms to form stable structures with low oxygen coordination, results in nearly identical vacancy concentrations in the InO1.5 and GaZnO2.5 layers in InGaZnO4, and only an order of magnitude lower concentration in the AlZnO2.5 layer as compared to the one in the InO1.5 layer in InAlZnO4. The presence of two light metal constituents in the InAlCaO4 along with Ca failure to form a stable fourfold coordination as revealed by its negligible relaxation near the defect, leads to a strong preference of the oxygen vacancy to be in the InO1.5 layer. Based on the results obtained, we derive general rules on the role of chemical composition, local coordination, and atomic relaxation in the defect formation and propose an alternative light-metal oxide as a promising constituent of multicomponent functional materials with tunable properties.

Effect of Zr-Ti combined deoxidation on the microstructure and mechanical properties of high-strength low-alloy steels

“…It is obvious that Ti2O3 is the only oxide with cation vacancy, while the others, have lower anion vacancy energies. These results are in good agreement with previous work [16][17][18][19][20][21][22][23].…”

Room Temperature Reactive Deposition of InGaZnO and ZnSnO Amorphous Oxide Semiconductors for Flexible Electronics

“…The observed trends may be caused by oxygen vacancy variations, which determine the final free electron concentration in the sputtered films. In keeping with the study of A. Murrat [14] and G. H. Kim [15], oxygen vacancy distribution exhibits a trend with respect to Ga in InGaZnO4, since the Ga ions have a stronger chemical bond with oxygen compared to Zn and In atoms. Accordingly, we can conclude that with increasing Ga atomic content the electron concentration is suppressed and the IGZO films' conductivity steeply decreases.…”

Hydroxyl radical-assisted decomposition and oxidation in solution-processed indium oxide thin-film transistors

“…35 In the near-VBM state, the localized states are reportedly occupied by electron-acceptors which consist of oxygen sites and low valence cations (In 3+ from In 4d and 5s). 13 In the near-CBM state, on the other hand, the band consists of electron-donors. The donor-type states are occupied at a neutral charge and can provide electrons by ionization.…”

“…These charge defects include metal interstitials, oxygen deficiencies, and carbon impurities. For In 2 O 3 , oxygen deficiency formation is inevitable owing to its low formation energy, 13 and therefore oxygen binders such as Hf, W, and Si must be doped to achieve a low trap density which leads to high quality In 2 O 3 -based films. 14,15 The addition of dopants requires higher annealing temperatures to achieve a satisfactory level of field effect mobility as that of undoped In 2 O 3 .…”