The increasing demand for new opto-electronics devices such as solar cells, laser diodes (LD), and high-brightness light-emitting diodes (HBLED), combined with the economic necessity to achieve lower energy consumption levels and higher device yields, is motivating researchers to develop new materials. The semiconductor industry is actively looking for alternatives to silicon, for example, to address new niche market applications in power devices. Constant efforts employed to reduce production costs are leading manufacturers to grow GaN on silicon substrate, creating new technical challenges, especially regarding the control of defect density on wafer. For all these reasons many studies are being initiated to improve understanding of the fundamental physical properties and behavior of compound semiconductor materials used in quantum wells, quantum dots and nanowire-like structures. Cathodoluminescence (CL) is a spectroscopy method that can generate reliable, quantitative, and stable data for research as well as prepare a basis for quality control during production.