I would like to make photoluminescence measurements of GaN material at room temperature. At the moment I do not have a laser that I could use for this purpose. Can I replace the laser with an LED?
What are the disadvantages of such a solution?
Thank you very much for your help!
Dear Piotr Pokryszka,
The reason to use a laser instead of a LED light source is that laser is monochromatic light and higher intensity. You could get high signal/noise ratio of photoluminescence using a laser source.
If your samples have strong absorption in a LED emission, you should be able to detect the photoluminescence in your samples without a problem. However, sometimes a LED light source has second order of peak at its emission. Make sure you avoid the second order of a LED emission when you try to measure your samples for their PL.
Thank you very much for your reply Xuhua Wang . By stimulating the sample with an LED I was able to observe photoluminescence. However, the signal observed was small.
So by stimulating the sample with an LED the obtained photoluminescence spectrum will be more "blurred"?
@Piotr Pokryszka
You need to use an intensified LED source and its emission has to match the maximum absorption peak of your samples. The cooling CCD spectrophotometer can get a good signal detections.
@ Xuhua Wang
In order to observe clearly the photoluminescence from GaN I should increase the optical power with which I excite the sample?
I observed a small photoluminescence spectrum at an optical power of 2mW and a wavelength of 272 nm ( about FWHM - 10 nm).
Dear Piotr Pokryszka ,
I will not repeat what has been said by the colleagues.
You can use LED array and collimate their light by a lens.
This will give you nearly monochromatic light with high intensity.
You can use also power LEDS. It can also excite the electrons from the valence band to conduction band according to its yellow and blue mixed light.
I would advise you to try them you will not loose nothing, you will gain.
Best wishes
Greenham, N. C., I. D. W. Samuel, G. R. Hayes, R. T. Phillips, Y. A. R. R. Kessener, S. C. Moratti, A. B. Holmes, and R. H. Friend. "Measurement of absolute photoluminescence quantum efficiencies in conjugated polymers." Chemical physics letters 241, no. 1-2 (1995): 89-96.
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