Studies of Light Emission from N-B doped 6H-SiC

Sammanfattning: The purpose of this thesis work was to find a way to measure basic light emission properties of nitrogen-and-boron-doped 6H-SiC, which are fabricated with a growth method developed at Linköping University. The research is in its initial phase and the light properties as well as optical measurement techniques are important. The aim is that the results of the measurements will provide feedback to the growth process what quality and doping levels that are required to get the maximum amount of light. The measurements were performed at the Laboratory of Lighting Technology, Technical University of Darmstadt, Germany. Two measuring methods with different excitation sources were tested: a double monochromator and a setup using near UV-filters. While the double monochromator was able to project wavelengths in steps down to 0.5 nm with a high accuracy, the filters were only available in steps of 10 nm where the accuracy of the wavelength values varied. The double monochromator was chosen for the continuing measurements. When using excitation light between 375-390 nm the emitted light was in the visible wavelength region. The light properties measured were the irradiance (measured in W/m2) and the peak wavelength were maximum luminescence occurred. The result showed that sample 2-4 had a peak wavelength at approximately 580‑582 nm for the excitation wavelength 375 nm. For sample 5 the peak wavelength occurred at 582 nm at the excitation wavelength 390 nm. Sample 1, the unintentionally doped, did not show any measurable results as expected. When irradiance of the excitation light was approx. 8 W/m2 the irradiance at the peak of luminescence for the samples varied between 15.03-29.35 mW/m2. The low values are believed to be the result of the emitted light scattering in all directions whereas the measurements are done in one direction and only from a small area of the sample. The measurements has shown that it is possible to measure the light properties of the grown material even though the samples were not finalized (capsulated) LED’s. The results from the measurements are of interest for the continuing development of the material.