Abstract: A method for etching a surface including obtaining a structure comprising a plurality of nanowires on or above a substrate and a dielectric layer on or above the nanowires, wherein the dielectric layer comprises protrusions formed by the underlying nanowires; reacting a surface of the dielectric layer with a reactant, comprising a gas or a plasma, to form a reactive layer on the dielectric layer, wherein the reactive layer comprises a chemical compound including the reactant and elements of the dielectric layer and the reactive layer comprises sidewalls defined by the protrusions; and selectively etching the reactive layer, wherein the etching etches the protrusions laterally through the sidewalls so as to planarize the surface and remove or shrink the protrusions.

Abstract: A method of making a film comprising depositing magnesium and boron on a substrate; depositing a capping layer to form a capped film; and cooling the capped film so as to form a magnesium diboride film. The depositing may comprise tuning a ratio of the Mg to the B so as to tailor a resistivity of the magnesium diboride film anywhere in the range 10 ??*cm???500 m?*cm, and so as to form the magnesium diboride film comprising a superconductive film having a critical temperature greater than 10K or in a range 10K-40K. The magnesium diboride film can have an area greater than or equal to a circular area having a diameter of at least 4 inches; a thickness and sheet resistance varying by less than 10% over an entirety of the area; and a surface roughness less than 2 nm over the entirety of the area.

Abstract: A method for etching a surface including obtaining a structure comprising a plurality of nanowires on or above a substrate and a dielectric layer on or above the nanowires, wherein the dielectric layer comprises protrusions formed by the underlying nanowires; reacting a surface of the dielectric layer with a reactant, comprising a gas or a plasma, to form a reactive layer on the dielectric layer, wherein the reactive layer comprises a chemical compound including the reactant and elements of the dielectric layer and the reactive layer comprises sidewalls defined by the protrusions; and selectively etching the reactive layer, wherein the etching etches the protrusions laterally through the sidewalls so as to planarize the surface and remove or shrink the protrusions.