4 ms·

Dude silicon absorbs below 900nm. We are talking about IR here.

• analog31 5y ago
  Just to clarify, so we're on the same page, silicon is the most common detector material for visible and UV. It absorbs a photon by kicking an electron into the conduction band, which is then swept to an electrical terminal and registered as a voltage or current. Silicon transmits IR, and can be used for optics and waveguides. So there's two sides to silicon, with the transition in that regime of about 900 nm. Actually, silicon photodiodes work down to about 1050 or even 1100 nm, but at a rapid loss of sensitivity and temperature stability. On the UV end, the silicon might be perfectly friendly, but the layers of stuff on top of the silicon become problematic. Silicon is also used for higher energy particles, just due to the havoc caused by absorbing an X or Gamma ray.
  • mmmBacon 5y ago
    True. But short wavelengths are inappropriate for these kinds of devices generally. ~1300nm is the sweet spot for silicon photonics.
    • analog31 5y ago
      Yeah, that's actually a hassle for miniaturizing optics because at any given wavelength, you can make optics out of silicon, or detectors, but not both. The IR detector materials all have their tradeoffs, of course.