Abstract
In recent years, significant efforts have been devoted to the research and development of spin-coated Al2O3 thin films, due to their large band gaps, high breakdown voltage and stability at high annealing temperature. However, as the alumina precursor has a large surface energy, substrates need to be treated by plasma before spin coating. Therefore, to avoid the expensive and process-complicated plasma treatment, we incorporated zirconium nitrate into the aluminum nitrate solution to decrease the surface energy of the precursor which improve the spreadability. Then, the electrical performances and the surface morphologies of the films were measured. For comparison, the pure Al2O3 films with plasma treatments were also prepared. As a result, after low temperature annealing (200 °C), the relative dielectric constant of Zr–AlOx spin-coated thin-film MIM (Metal-Insulator-Metal) devices can reach 12 and the leakage current density is not higher than 7.78 × 10−8 A/cm2 @ 1 MV/cm when the concentration of zirconium nitrate is 0.05 mol/L. The Aluminum oxide film prepared by zirconium doping has higher stability and better electrical properties than the pure films with plasma treatments and high performance can be attained under low-temperature annealing, which shows its potential application in printing and flexible electronic devices.
Highlights
Regarded as one of the keys for the stability of thin-film transistors, the dielectric layer has a great influence on the performance of thin film transistor (TFT) devices
The results show that Zr doping can increase the wetting ability and smooth the surface of aluminum oxide dielectric layer, and can increase the uniformity and density of aluminum oxide dielectric layer
For the deposition of Al2 O3 and Zr–AlOx gate dielectric layers by a solution process, precursor solutions for each gate dielectric were prepared by dissolving metallic precursors in an ethylene glycol monomethyl ether (EGME) solvent
Summary
Regarded as one of the keys for the stability of thin-film transistors, the dielectric layer has a great influence on the performance of thin film transistor (TFT) devices. In the studies of metal oxide dielectric layers, Al2 O3 has a high dielectric constant (k = 8.6–10) and large band gap (~9 eV) [16]. Avis et al found the TFT made with solution processed AlOx gate dielectric presents high field-effect mobility with lower interface trap density [21]. High-quality metal oxide dielectric often requires higher annealing temperature [35], whereas it contradicts the low-temperature processing required by flexible devices [36]. The MIM devices of Zr–AlOx fabricated by spin-coating show high relative dielectric constant and low leakage current density at a low annealing temperature process. It proves the applicability of this approach for printed and flexible electronic devices
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