Control of native defects in III-nitride-based light emitters

The luminescence efficiency of a light emitter based on III-nitrides, such as GaInN/GaN quantum well, can be influenced by defect-assisted non-radia\-tive recombination, making it a highly sensitive detector of defects with nanometer-scale spatial resolution. This thesis takes advantage of that and investigates the non-radiative carrier lifetime in GaInN/GaN single quantum wells and its relation to the growth condition of each layer in the semiconductor nanostructure. As a first conclusion, thermally activated diffusion of point defects leading to non-radiative recombination is a universal mechanism present during III-nitride growth. Various aspects of the diffusion process are characterized. A forward diffusion is observed in the direction of growth. Diffusion properties of the defect, such as diffusion coefficients, and migration energy are determined. Vacancies are identified as likely the defects that are diffusing, and acting as non-radiative center, with nitrogen vacancies more likely involved. The major sources of vacancies are likely the nucleation layer and the GaN substrate for heteroepitaxy and homoepitaxy, respectively, and the growing surface of subsequent layers are considered potentially secondary sources. As a second conclusion, vacancy diffusion is likely a predominant mechanism related to thermal damage processes observed while growing layers on top of the quantum well, e.g. a p-layer, and activated after growth, e.g. annealing. Alongside this, the formation mechanism of vacancies is study. The combination of both mechanisms, defect diffusion and defect formation, enable to further reduce the non-radiative recombination, i.e. the vacancy density, in the quantum well. Therefore, performance and reliability of light-emitter devices of all emission wavelengths can be improved by properly controlling the native defect diffusion.