system
Given the following post, respond as if you're commenting on Reddit:
human
Why can't LEDs produce radio waves or x-rays?

Is it that we just haven't been able to produce an LED with the right bandgap? Are we just not interested in the production of non visible LEDs (with the exception of UV and some IR) or is there a more fundamental reason? And as a follow up question: If we could create a radio wave LED, could we transmit radio wave signals with it?
gpt
You already know how bandgaps work.  We'd absolutely *love* to directly image high and low wavelengths, but it's probably not possible.

For high energy waves above UV, you're talking about ionizing radiation.  If the photon being released has enough energy to ionize an atom, it very likely is ionizing the atoms in the emission source as well.  That will rapidly destroy any semiconductor junction.  You'd need a material that's far more stable than anything else.  You sould use lots of insulators to emit high energy photons except for the fact that when you give an electron that much energy it would rather just rearrange chemical bonds/cause a fire.

For low frequency photons you're talking about a small band gap.  Visible light is on the order of an electron volt.  Lead sulfide is an example of a very low-gap semiconductor used for IR LEDs- about .37 eV.  A 100 MHz photon from an FM radio station has ~.4 millionths of an eV.  It's not really practical to make a band gap smaller than IR.