Tuning the band gap and nitrogen content of ZnOxNy thin films deposited by reactive HiPIMS

We show that it is possible to manipulate the stoichiometry and composition of the thin films deposited by reactive high power impulse magnetron sputtering (HiPIMS) by the design of the discharge pulsing scheme. This is illustrated for the case of the short-pulse HiPIMS of a pure Zn target in Ar/N2/O2 mixture gas (low content of O2), where the variation of the discharge pulsing frequency has led to depositions of crystalline ZnOxNy thin films with the nitrogen content and optical band gap values ranging from 0 to 6.2 at.% and from 3.34 to 1.67 eV, respectively. The fine control of nitrogen content in the deposited ZnOxNy thin films was obtained by the use of smooth transitions of the reactive HiPIMS discharge between the compound and metallic target sputtering modes. Thus, the yield of the sputtered metal atoms was controlled by the discharge pulsing frequency from low values, in the compound target sputtering mode, to large values, in the metallic target sputtering mode. The controlled amount of metal atoms in the gas phase and the limited amount of oxygen in the deposition chamber determined depositions of films with variable content of nitrogen.