long-term stability of AlGaN/GaN photodiodes @ 254nm?

Discussion in 'The Projects Forum' started by forumairman, Jul 24, 2008.

  1. forumairman

    Thread Starter New Member

    Jul 24, 2008
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    I am researching photodiodes and cannot find any definitive data on the long term stability of AlGaN/GaN photodiodes or even which type is better. From the prices I would have to guess that AlGaN ones are better quality but anyone who is, or thinks they are, an expert on them please feel free to get back to me with your thoughts.

    Also, if anyone has any idea how these photodiodes compare with SiC ones, let me know as well.

    Thanks!
     
    Last edited: Jul 24, 2008
  2. scubasteve_911

    Senior Member

    Dec 27, 2007
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    http://nina.ecse.rpi.edu/shur/GaNphoto/index.htm

    What do you mean by stability? There are many classes of this characteristic.

    Cause: aging, temperature cycling, repeatability
    Effect: sensitivity drift, increased dark current, noise?

    Quality isn't a property of the materials used to perform some function, I think you must mean performance. Probably quantum efficiency at some wavelength, which is explained in the above link.

    Steve
     
  3. forumairman

    Thread Starter New Member

    Jul 24, 2008
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    Thanks for the reply. I have visited the website that you posted before, and there is some good data there for sure, but if you went through the slide show you probably noticed the horrid quality of them. I have since contacted the author and requested the original.

    I modified what the title should be because I am after the effect on the output of the photodiode after prolonged exposure to 254nm light. Some photodiode types experience extreme degradation of the output signal after a few thousand hours of exposure.

    Ideally I am looking for a "% of initial response VS hours of exposure to 254nm" graph for an AlGaN photodiode.

    Thanks!
     
  4. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    What in the world are you doing at 2537 A°? We always used photomultipliers, but that was 40 years ago. The only way I know to assess stability of your photodiode is to try it in comparison with some standardized actinometric method. John
     
  5. forumairman

    Thread Starter New Member

    Jul 24, 2008
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    The application is measuring the output of a germicidal UV lamp. I am only concerned with 254nm light. A photomultiplier requires too large a voltage and is also a bit too bulky. I only have 28VDC maximum available and limited space.

    Thanks for the suggestion though.
     
  6. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    If you need good quantitation and do not have a standard, conventional chemical actinometric methods are the way to go. John
     
  7. scubasteve_911

    Senior Member

    Dec 27, 2007
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    I'm sorry, I cannot find any information out there on this. I did a good search of IEEE papers online, but nothing turned up. I will check out IOP later on

    Steve
     
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