Microwave irradiation-assisted method for the deposition of adherent oxide films on semiconducting and dielectric substrates

We report a method for the deposition of thin films and thick coatings of metal oxides through the liquid medium, involving the microwave irradiation of a solution of a metal-organic complex in a suitable dielectric solvent. The process is a combination of sol-gel and dip-coating methods, wherein coatings can be obtained on nonconducting and semiconducting substrates, within a few minutes. Thin films of nanostructured ZnO (würtzite) have been obtained on Si(100), glass and polymer substrates, the nanostructure determined by process parameters. The coatings are strongly adherent and uniform over 15 mm × 15 mm, the growth rate ∼ 0.25 μm/min. Coatings of nanocrystalline Fe₂O₃ and Ga₂O₃ have also been obtained. The method is scalable to larger substrates, and is promising as a low temperature technique for coating dielectric substrates, including flexible polymers.