Crystalline In–Ga–Zn–O Density of States and Energy Band Structure Calculation Using Density Function Theory

Abstract

The density of states (DOS) and energy band structure of crystalline In-Ga-Zn-O (c-IGZO) and the impact of point defects on its electronic structure are investigated by first-principles calculations based on the density function theory. The calculated DOS showed that the p-orbitals of the oxygen atoms mostly contribute to the valance band maximum (VBM) of c-IGZO. The conduction band minimum (CBM) is dominated by s-orbitals of the Zn/Ga mixture atoms, while the In atoms have the largest spatial spread of wave function. Oxygen vacancies create fully occupied defect states within the band gap and serve as deep donors. Both hydrogen substitutions and interstitials act like shallow donors, and raise the Fermi level above the CBM. Oxygen split interstitials created fully occupied defect states above VBM, while oxygen octahedral interstitials create both occupied and unoccupied states, and may serve as acceptors.

Synthesis of InGaZnO4 nanoparticles using low temperature multistep co-precipitation method

“…Finally, the single phase of IGZO was formed when the calcination temperature reached 1100 C. All reflections can be indexed as the rhombohedral symmetry structure [JCPDS No. 38e1104] [26].…”

“…It is indicated that the tablets is suitable for future application as sputtering target. The relative density of IGZO disk was calculated based on the theoretical density of 6.38 g cm À3 by assuming a rhombohedral symmetry structure with lattice pa- [26,27].…”

“…All reflections can be perfectly indexed as the rhombohedral symmetry structure [JCPDS No. 38e1104] with its lattice parameters of a g ¼ 120 [26]. Moreover, Scherrer equation is a formula that relates the size of particles, or crystallites, in a solid to the broadening of a peak in a diffraction pattern as shown in equation (1),…”

Properties of crystalline In–Ga–Zn-oxide semiconductor and its transistor characteristics

“…Figure 17(b) shows the carbon concentration profiles. As is true with hydrogen, the concentration of carbon in sample (B) is lower than that in sample (A), and this result suggests that the concentration should be approximately 10 19 atoms/cm 3 or lower for high crystallinity. That is, the amount of impurities in a film should be minimized to form a high-quality CAAC-IGZO film.…”

“…A strong (009) peak appears at 2ª = 31°, which is the same as that for IGZO(009) observed from CAAC-IGZO. 10) Figure 8 shows electron backscatter diffraction (EBSD) patterns of the IGZO target. This target does not have an amorphous structure and is polycrystalline.…”