Aqueous-based synthesis of gallium tungsten oxide thin film dielectrics. Issue 13 (17th February 2015)

• Record Type: Journal Article
• Authors: Oleksak, Richard P.; Stickle, William F.; Herman, Gregory S.
• Is Part Of: Journal of materials chemistry. Volume 3:Issue 13(2015)
• Page Start: 3114
• Page End: 3120
• Publication Date: 2015-02-17
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c4tc02985b
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : Gallium tungsten oxide thin films formed from a single aqueous precursor. The highly controllable metal content allowed for fine-tuning of film dielectric and optical properties. Abstract : An aqueous-based approach to the deposition of gallium tungsten oxide thin film dielectrics was developed where the metal content (Ga2− x W x /2 O3− δ, x = 0.31–0.66) can be controlled by the initial precursor concentrations, while the oxygen deficiency ( δ ) can be controlled by post annealing. The spin-coated precursor converts to an amorphous oxide thin film with uniform distribution of metal cations after heating to 400 °C. The Ga2− x W x /2 O3− δ band gap decreased with increasing W content from 4.9 eV for the undoped film (Ga2 O3 ) to 4.6 eV for the film with the highest W content (Ga1.34 W0.33 O3− δ ). The electronic properties of the dielectric films significantly improved with incorporation of W, where a decrease in leakage current and an increase in breakdown field strength from 2.9 MV cm −1 (Ga2 O3 ) to 5.2 MV cm −1 (Ga1.34 W0.33 O3− δ ) was observed. Prior studies have suggested that Ga2− x W x /2 O3− δ thin films can form dense low- k dielectric materials, where the relative amount of W in the film can significantly modify the dielectric constant. However our studies found no significant decrease in the dielectric constant with W doping of Ga2 O3 . We found that annealing the films >400 °C in air resulted in the formation of sub-stoichiometric WO x and metallic W throughout the films which may complicate dielectric measurements.