Atomic and electronic structures at ZnO and ZrO₂ interface for transparent thin‐film transistors

Abstract

In this paper, we report the studies of atomic and electronic structures at ZnO and ZrO 2 interface. The epitaxial heterostructures were grown by laser molecular beam epitaxy and the interface atomic structure was determined by using highresolution transmission electron microscopy (TEM). Band alignment for high-k ZrO 2 layer on ZnO was investigated by in situ X-ray photoemission spectroscopy (XPS) characterization and first-principles calculations based on density functional theory (DFT). The valence and conduction band offsets (CBOs) were found to be 0.27 AE 0.05 eV and 2.16 AE 0.05 eV, respectively. The results are in good agreement with values from theoretical calculations. The large CBO and small lattice mismatch between ZnO and ZrO 2 suggest potential for ZrO 2 to be used as a gate dielectric in ZnO-based transparent electronic devices.

UV‐Assisted Low Temperature Oxide Dielectric Films for TFT Applications

“…Such compounds possess high dielectric constants, large conduction band offsets and excellent solvent resistance. [14][15][16] These materials are generally vacuum deposited [6,7,15] or require relatively high post-annealing temperatures. [17][18][19][20] 3…”

Room Temperature Processed ZnO Thin Film Transistors Grown by Magnetron Sputtering Using Zirconium Oxide Gate Dielectric

“…It was found that the lattice mismatch between the two layers is ≈10%. This is in fact lower than the standard ZnO‐SiO 2 interface as observed by Wang et al High leakage current observed in Figure could be due to non‐patterned active channel layer, rather than the quality of the dielectric layer . One of the other contributors could be the lattice mismatch between the two layers.…”

Photoluminescence enhancement of ZnO nanowire arrays by atomic layer deposition of ZrO2 layers and thermal annealing

“…5. 48 In type-I core/shell systems, the excited electron-hole pairs are efficiently confined to the ZnO core, leading to a stronger spatial overlap of the wave functions of all the electrons and holes, which will further improve the NBE emission of ZnO. However, the NBE emission intensity decreases with the further increase of ZrO 2 shell thickness to 150 ALD cycles.…”

“…It is well known that zirconium oxide (zirconia, ZrO 2 ) has a high dielectric constant (20)(21)(22)(23)(24)(25) and a relatively large band gap (B5.80 eV) which can be used as a desirable gate dielectric in ZnO-based transparent electronic devices. [29][30][31][32] The ZnO-ZrO 2 heterostructures are also stable and exhibit good UV-shielding properties due to their excellent thermal and chemical stability. 33 Plank et al reported that the photoconversion efficiency of ZnO nanorod-based dye-sensitized solar cells is extremely enhanced with a thin ZrO 2 energy barrier.…”