Method for producing transparent conductive coatings for emi protection using HiPIMS

A method for forming a coating on a substrate, the method comprising:

• growing a zinc sulfide (ZnS) film on a surface of the substrate with a radio frequency (RF) sputtering process;
• and
• sputtering metal dopants on the substrate at concentrations between 1×1016 cm−3 and 1×1020 cm−3 with a high-power impulse magnetron sputtering (HiPIMS) process, wherein:
• the metal dopants are ionized and one of molybdenum or tungsten;
• the metal dopants are simultaneously sputtered with a RF sputtering process while growing the ZnS film, wherein:
• the RF sputtering process and HiPIMS process are simultaneously performed such that the ZnS film is grown on the substrate during the RF sputtering process;
• and
• the HiPIMS process is performed such that the ionized metals dopants are interspersed in the ZnS film as the ZnS film is grown on the substrate;
• the sputtering the metal dopants ionizes the coating on the substrate such that the coating has a sheet resistance that is less than 50 ohm/square and the metal dopants form n-type dopants in the ZnS film;
• and
• the concentrations at which the metal dopants are sputtered varies with a thickness of the ZnS film such that at a first ZnS film thickness, there is a first concentration and at a second ZnS film thickness that is greater than the first ZnS film thickness, there is a second concentration that is less than the first concentration where the second ZnS film thickness is separate from the first ZnS film thickness, wherein:
• the ZnS film is formed in a stepwise fashion to achieve the first and second film thicknesses with corresponding gradient concentrations of the metal dopants distributed throughout the coating;
• and
• the greater thickness of the second ZnS film dilutes the metal dopants throughout the coating thereby allowing for a lower concentration of the metal dopants.