Evaluation of defects in cuprous oxide through exciton luminescence   imaging
  The various decay mechanisms of excitons in cuprous oxide (Cu2O) are highly sensitive to defects which can relax selection rules. Here we report cryogenic hyperspectral imaging of exciton luminescence from cuprous oxide crystals grown via the floating zone method showing the samples have few defects. Some locations, however, show strain splitting of the 1s orthoexciton triplet polariton luminescence. Strain is reduced by annealing. In addition, annealing causes annihilation of oxygen and copper vacancies, which leads to a negative correlation between luminescence of unlike vacancies. 
Laszlo Frazer, Erik J. Lenferink, Kelvin B. Chang, Kenneth R.   Poeppelmeier, Nathaniel P. Stern, John B. Ketterson
cond-mat.mtrl-sci