Assignment of deep levels causing yellow luminescence in GaN

Abstract

The deep levels causing yellow luminescence transitions in GaN were investigated using photoluminescence, hall measurements, and deep level transient spectroscopy (DLTS). The presence of donor levels at ~18, ~35, ~70 meV, which are respectively associated with the Si shallow donors, O impurities, and the nitrogen vacancies were observed when the Si-doped GaN were measured. Reduction in yellow luminescence was observed when the thermal annealing of nitrogen ambient is done at 750°C. The results showed that yellow luminescence in GaN arises from the transitions from the Ec∓ (0.2∓0.24) eV levels to the deep level at Ev +0.87 eV.