Stability Studies on Nitrogen Doped p-ZnO (NZO) Thin Films Grown by Reactive Magnetron Sputtering

Nitrogen doped ZnO (NZO) thin films, at different N-2 flow rates have been deposited on glass substrates by pulsed DC reactive magnetron sputtering technique. The effect of N-2 flow rate (1.0 sccm -3.0 sccm) on the structural, optical, electrical and chemical state of N has been studied. With the effect of N-2 flow rate: the crystallinity of the films decreased, tensile stress is developed, optical transmittance decreased (80% to 60%), conductivity decreased till 1.5 sccm and films were n-type conducting. At 2.0 sccm and 2.5 sccm of N-2 flow rates, NZO thin films showed p-type conductivity. The changes in the magnitude and type of conductivity have a direct relation with the changes observed in N-chemical state in ZnO lattice. p-NZO thin films are electrically unstable; this instability has been explained based on the changes occurred in the N chemical states, resulting from the stress release in NZO lattice.