Pervasive Shallow Donor Impurities in GaN

Abstract

Understanding the nature of defects and their role on fundamental physical properties of semiconductors is essential to obtain the necessary material control to reach the full realization of their technological potential. High-resolution infrared measurements in combination with high-sensitive SIMS of unintentionally doped GaN films unambiguously identified Si and O shallow donors and yielded their ground state binding energies. High-resolution, variable-temperature photoluminescence studies of recombination processes associated with excitons bound to donors leaving the donors in the ground states and excited states after exciton annihilation are in excellent agreement with the energies of donor intra-impurity transitions measured by infrared absorption. Photoluminescence studies of unintentionally doped and doped GaN films clarified conflicting aspects of donor identification and binding energies of shallow pervasive Si and O donors. These results provided the experimental foundation for the detection and identification of pervasive shallow donors in GaN by optical methods.