High-quality dielectric suitable for use with amorphous semiconductors

Very-high-quality Al/SUB 2/O/SUB 3/ films have been grown by anodizing aluminum films in a bath of tartaric acid, buffered with NH/SUB 4/OH and diluted with propylene glycol. Several thousand films were evaluated to demonstrate high resistivities and breakdown voltages, as well as dielectric properties stable with respect to film thickness, frequency, and applied voltage. It is shown that an optimum solution, an optimum buffer, an optimum pH, and an optimum anodization time exist.