Establishment of the conditions to improve the luminescence properties of ZnSe for application as scintillating bolometer in the search for neutrinoless double beta decay

The improvement of luminescence/scintillation properties of zinc selenide is the key to reduce the detection background for its application as a scintillating bolometer in experiments that search for neutrinoless double beta decay. This rare event is predicted in extensions of the Standard Model and carries important information about the nature of neutrinos and their mass scale. If detected, new perspectives involving symmetry breaking may be explored in particle physics. In this work we investigate by photoluminescence and complementary techniques the luminescence properties of ultra-pure polycrystalline zinc selenide samples grown by the chemical vapor deposition (CVD) method and submitted to thermal treatments, gamma and particle irradiations, as well as doping processes with aluminum and gallium by diffusion and ion implantation. The results on this work demonstrate that the improvement of the luminescence of zinc selenide depends of the controlled introduction of shallow donor impurities into the material. Furthermore, pair defects involving shallow donor impurities and deep zinc acceptor vacancies (A-centers) - responsible for luminescence bands in the yellow to red spectral region according to the literature - are demonstrated to be the most efficient centers of radiative recombination in the material.