Zinc oxide film and method for making

Abstract

A method for depositing a solid film of ZnO onto a substrate from a reagent solution includes a reservoir of reagent solution maintained at a sufficiently low temperature to inhibit homogeneous reactions within the reagent solution. The reagent solution contains a source of Zn, a source of O, and multiple ligands to further control solution stability and shelf life. The chilled solution is dispensed through a showerhead onto a substrate. The substrate is positioned in a holder that has a raised structure peripheral to the substrate to retain or impound a controlled volume (or depth) of reagent solution over the exposed surface of the substrate. The reagent solution is periodically or continuously replenished from the showerhead so that only the part of the solution directly adjacent to the substrate is heated. A heater is disposed beneath the substrate and maintains the substrate at an elevated temperature at which the deposition of a desired solid phase from the reagent solution may be initiated. The showerhead may also dispense excess chilled reagent solution to cool various components within the apparatus and minimize nucleation of solids in areas other than on the substrate. The deposited film may be annealed after deposition and may be doped to enhance selected characteristics. The ZnO films made by the process have distinctive electrical and optical properties and are suitable for a variety of electronic and optical devices.