Yellow luminescence and related deep levels in unintentionally doped GaN films

The deep level energy distribution associated with the well-known "yellow l uminescence" in GaN is studied by means of two complementary deep level tec hniques: photoluminescence and surface photovoltage spectroscopy. The combi ned experimental results show that the yellow luminescence is due to captur e of conduction band electrons, or electrons from shallow donors (with a ma ximum depth on the order of the thermal energy) by a deep acceptor level wi th a broad energy distribution, centered at similar to 2.2 eV below die con duction band edge. In addition, the results show that the density of yellow luminescence related states possesses a significant surface component. [S0 163-1829(99)16215-5].