Solution-Processed Aluminum Oxide Phosphate Thin-Film Dielectrics

Aluminum oxide phosphate thin films have been deposited via spin coating from aqueous solution and utilized as gate dielectrics in thin-film transistors. Films are atomically smooth, dense, and amorphous, while exhibiting excellent morphological stability to 1000 °C. Film chemistry and structure are investigated by using an array of analytical techniques including X-ray diffraction, FT-IR spectroscopy, and electron-microprobe analysis. Dielectric film functionality and quality are explored through integration in capacitor and thin-film transistor devices. Film permittivity for an Al2PO5.5 composition is found to be 4.8 in combination with leakage current densities <10 nA cm-2 at 1 MV cm-1 and current-limited breakdown fields up to 10 MV cm-1. Thin-film transistors fabricated with these oxide phosphate dielectrics and sputtered ZnO channels exhibit strong field-effect and current saturation with incremental mobilities up to 3.5 cm2 V-1 s-1. The ability of the amorphous matrix to accommodate additional oxid...