Realization of high-quality RF sputtered ZnMgO (x=15%) thin films by post-growth annealing treatment

ZnMgO, a direct wide-bandgap material with high exciton binding energy, has received widespread research attention in optoelectronics. However, its inherent n-type doping facilitates defect-related visible emission, which hampers the required luminescence properties in the UV region. Also, ZnMgO requires post-growth treatment which releases accumulated strain energy, modulates defect states, expands crystallite size, and augments ad-atoms interdiffusion, thereby affecting its bandgap. This work reports the influence of post-deposition annealing parameters like temperature and time on RF sputtered Zn0.85Mg0.15O thin films using rapid thermal annealing. The study showed that high temperature annealing aided Mg incorporation in ZnO lattice together with an increase in the grain size due to aggregation of grains. Highest activation energy, 78 meV, and narrowest line width, 34 meV, for D degrees X peak of 900 degrees C annealed film was obtained from photoluminescence study. Increasing annealing temperature also showed dissociation of bound exciton peaks into corresponding localized and delocalized exciton states.

Automated summary

This study investigated the impact of post-deposition annealing parameters on RF sputtered Zn0.85Mg0.15O thin films, showing that high temperature annealing facilitated Mg incorporation in ZnO lattice and increased grain size due to grain aggregation. High activation energy and narrow line width were achieved in the 900 degrees C annealed film, with the dissociation of bound exciton peaks observed at increasing annealing temperatures.