Gallium Nitride materials are direct bandgap semiconductors with important applications, such as in the production of light-emitting diodes and transistors. The process of photoluminescence, in which excited electron and holes emit electro-magnetic radiation when they recombine, can be used to study the structure and quality of Gallium Nitride materials. Due to the size of the bandgap in these materials (3.4eV), ultraviolet light is required to create electron-hole pairs in GaN. We designed and built a system, which uses ultraviolet light, to take measurements on GaN samples provided by a local company, Lightwave Photonics, who were interested in the quality of the materials they develop and produce. Our system uses a ultraviolet LED as a light source instead of an expensive UV laser. It uses two short-pass filters and a long-pass filter to isolate the luminescence from the sample from excitation source. A spectrometer measures intensity of the luminescence versus wavelength. A camera is also used to observe the samples during set-up. The system was calibrated using radiation from a black-body source. We were able to take measurements on several samples. Our results agree with the expected emission spectra of GaN materials.
Pantova, Dona H.
"UV LED System for PL Measurements on GaN Samples,"
Macalester Journal of Physics and Astronomy: Vol. 7
, Article 6.
Available at: https://digitalcommons.macalester.edu/mjpa/vol7/iss1/6