N doped ZnO (N:ZnO) film prepared by reactive HiPIMS deposition technique

In this paper, we report a nitrogen (N) doped zinc oxide (N:ZnO) film grown by the reactive high power impulse magnetron sputtering (HiPIMS) technique on glass substrates, where nitrogen gas (N₂) is used as the N source. The proposal is to investigate the influence of process parameters on the alteration of the N:ZnO film from n- to p-type conductivity and the stability of the p-type behavior. It is obtained that the n- or p-type behavior of the as-deposited N:ZnO film is affected by the N₂ flow rate, deposition temperature, and inductively coupled plasma (ICP) assistance, of which the ICP assistance had a great impact. It is noticed that, owing to the improved ionization rate of the N₂ dopant by ICP, the N:ZnO film almost totally prefers to exhibit p-type behavior. Based on the measurement by temporal resolution optical emission spectroscopy, the components in plasma are obtained and the ion reaction in film growth is confirmed: a high concentration of active N⁺ in the ICP-assisted plasma reacts with sputtered Zn⁺ in vapor to form No defect in the p-type N:ZnO film. We then forecast that a stable p-type N:ZnO film can be grown using the HiPIMS technique.