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Light Emitting Diode under SEM

After examing the LED under an optical microscope, we placed it in the Scanning Electron Microscope, to examine it in further detail, and to try to identify the elements it was made of.

 

led01.tif


We then used X-ray analysis to try and identify the elements in the LED and this showed us that the LED was Gallium Phosphide. This agreed with our early photos of green light being given off by the LED, as a Pure GaP LED would emit green light, with a wavelength of around 555 nm.



LED


We could see a definitive line in the side of the LED after we turned it over, and we chose to investigate this further, to see if we could see any difference in the materials either side of this line. We perfomed a 'line scan' across the line, but did not find any difference in the concentrations. This is either down to the fact that there was no difference in the elements either side of the line, or if there were a difference, we probably would not detect it, as it is only a very small amount of doping.

 


LED side view