The Effects of Annealing Atmosphere on the Electrical Properties of MgNb₂O₆/ITO Heterostructures

Abstract

The effects of annealing atmosphere (N2, air and O2) on the electrical properties of sol–gel‐derived MgNb2O6/ITO heterostructures are discussed in this work. All samples exhibited the amorphous phase and were highly transparent. The percentage of Nb4+ content increased when the films were annealed in the oxygen‐deficient conditions, which could lead to semiconducting films. In addition, the results show that the electrical properties of sol–gel‐derived MgNb2O6 thin films could be tuned based on the annealing atmosphere. Moreover, the conduction mechanisms of MgNb2O6/ITO heterostructures are also discussed in this study. The results show that MgNb2O6 thin films have potential for use in multifunctional optoelectronic applications, due to their flexible electrical properties and good transparency.

The effects of zinc substitution on the electrical properties of MgNb2O6 thin films

“…The characteristic spectra of the 400°C-annealed films (x = 0, 0.2, 0.6, 1) are shown in Figure 4. The binding energy for Mg 2p and Zn 2p revealed divalent oxidation states, which are very similar to those found in our previous work [6,7]. The O 1s and Nb 3d spectra of the films could be decomposed clear shoulders (non-lattice oxygen and Nb 4+ ).…”

“…As the annealing temperature increased to 500°C, clear diffraction peaks identified as columbite-M 2+ Nb 2 O 6 (M = Mg or Zn) phase were observed. Based on the findings of our previous study [6,7], the crystalline temperature of the MNO films is over 600°C. These results indicated that the crystalline temperature of the magnesium-based columbite thin films could be effectively reduced by zinc substitution.…”

“…Therefore, the high dielectric constant and leakage current of the samples was more likely attributed to the density of the films. According to the past research [6], the fluctuation in the leakage current of the samples produced under various conditions may be due to the variation of the conduction mechanisms, which is related to the Nb 4+ (or oxygen vacancy) concentration. The re-plotted I-V curves shown in Figure 8 revealed that the calculated K values deviate from the expected ones (K ~ 4) [6].…”

“…In our previous work [6], highly transparent amorphous-MNO thin films on indium tin oxide (ITO)/glass substrates were fabricated by the sol-gel method, and the effects of annealing temperature and atmospheres (N 2 , air and O 2 ) on the electrical and optical properties of these films were also discussed [6,7]. The results indicated that the amorphous MNO thin films featured a high dielectric constant, low leakage current and good transparency after 500°C annealing.…”

“…Then, the precursor sol was spin-coated on the glass and ITO/glass substrates. The detail of the deposition procedure is shown in our previous work [6,7]. Finally, the Mg 1-x Zn x Nb 2 O 6 (MZ x NO) films were annealed at 400°C and 500° C for 30 min in air.…”