- #1
Griffin Kowash
- 3
- 0
Hi,
Lately I've been reading about a lab exercise in which Planck's constant is estimated using LEDs. Every procedure I've encountered states that the energy of an emitted photon (and by extension the potential across the semiconductor's band gap) is equal to the threshold voltage multiplied by the elementary charge.
My understanding is that the voltage applied across a diode serves to counteract the electric field created by the depletion region, allowing current to begin flowing. Considering this, it seems like the threshold voltage is related more to the depletion region than it is to the band gap of the semiconductor. I don't understand the connection there, and so far I haven't had any success trying to research it.
When I asked my physics professor, he told me that electric field of the depletion region depends directly on the semiconductor's band gap, which explains the Ephoton = eVthreshold equation. Unfortunately he didn't have time to say more, and I won't get a chance to talk with him for another week or so.
Does anyone have any insight to offer about why this equivalence is true?
Thanks,
Griffin
Here are a couple examples of the sort of lab exercise I'm referring to:
http://www.phys.uconn.edu/~hamilton/phys258/N/led.pdf
http://laser.physics.sunysb.edu/~kegan/Poster/poster.pdf
Lately I've been reading about a lab exercise in which Planck's constant is estimated using LEDs. Every procedure I've encountered states that the energy of an emitted photon (and by extension the potential across the semiconductor's band gap) is equal to the threshold voltage multiplied by the elementary charge.
My understanding is that the voltage applied across a diode serves to counteract the electric field created by the depletion region, allowing current to begin flowing. Considering this, it seems like the threshold voltage is related more to the depletion region than it is to the band gap of the semiconductor. I don't understand the connection there, and so far I haven't had any success trying to research it.
When I asked my physics professor, he told me that electric field of the depletion region depends directly on the semiconductor's band gap, which explains the Ephoton = eVthreshold equation. Unfortunately he didn't have time to say more, and I won't get a chance to talk with him for another week or so.
Does anyone have any insight to offer about why this equivalence is true?
Thanks,
Griffin
Here are a couple examples of the sort of lab exercise I'm referring to:
http://www.phys.uconn.edu/~hamilton/phys258/N/led.pdf
http://laser.physics.sunysb.edu/~kegan/Poster/poster.pdf