Photonic Characterization of Oxygen and Air-Annealed Zn3N2 Thin Films

Zinc nitride films were synthesized by reactive radio frequency (rf) magnetron sputtering of a zinc target using an Ar+N2 mixture. The as-deposited films were annealed in the air and O2 at 300 {\deg}C for 1 hr. The XRD measurements indicated that the films had a polycrystalline structure with a preferred (400) Zn3N2 orientation. The annealing process enhanced the crystallinity. After annealing, the AFM and SEM morphology revealed no significant change in the surface morphology and surface roughness. The direct bandgap of Zn3N2 was estimated to be in the range of 1.15 -1.35 eV where annealing resulted in a reduction of the bandgap. The films were confirmed to be p-type conduction and the resistivity was slightly increased by annealing. The photoconductivity measurements indicated that the as-deposited films did not have any photoresponse, whereas the annealed films exhibited photoconductivity.