Optical and structural comparison between nitrogen-doped and oxygen-rich ZnO thin films

Abstract

A ZnO thin film reactively sputtered at high oxygen pressure (O-rich) was compared to a nitrogen-doped ZnO (ZnO:N) thin film using optical and structural spectroscopies. X-ray diffraction measurements confirmed a high (0002) preferential orientation for both films. Absorption measurements revealed two intra-band-gap absorptions in addition to observed free exciton (FX) and neutral acceptor–bound exciton features in both films. Binding energies of the FXs were calculated to be 65 and 69 meV, respectively, for the ZnO:N and O-rich thin films at 15 K. Photoluminescence measurements revealed nearly the same characteristics, i.e. that the deep level emission is dominant. Recombination lifetime values of 577.35 and 797.46 ps were measured for ZnO:N and O-rich thin films, respectively.

Keywords:

• zinc oxide
• nitrogen doping
• p-type zinc oxide
• optical characteristics
• absorption
• photoluminescence
• recombination lifetime
• exciton