Changes

Jump to navigation Jump to search
396 bytes added ,  21:50, 11 October 2007
m
no edit summary
Line 19: Line 19:  
# A Photodiode is a diode that is especially sensitive to light. When it is reversed biased, it conducts when it is exposed to light and blocks current when it is in the dark. It contains a very thin doped region and a very thick depleated zone in which photons are absorbed. It is usually packaged in a clear glass or plastic case that allows light through to maximize the effect it has upon the diode.
 
# A Photodiode is a diode that is especially sensitive to light. When it is reversed biased, it conducts when it is exposed to light and blocks current when it is in the dark. It contains a very thin doped region and a very thick depleated zone in which photons are absorbed. It is usually packaged in a clear glass or plastic case that allows light through to maximize the effect it has upon the diode.
 
# An avalanche photodiode is a photodiode designed in such a way that it releases a pulse of electrons per photon instead of just one. When it is reverse-biased above the breakdown voltage, through the process mentioned above, the avalanche photodiode uses the energy from the photon to release photodiode from its metastable state and create a pulse.  
 
# An avalanche photodiode is a photodiode designed in such a way that it releases a pulse of electrons per photon instead of just one. When it is reverse-biased above the breakdown voltage, through the process mentioned above, the avalanche photodiode uses the energy from the photon to release photodiode from its metastable state and create a pulse.  
# Temperatures are caused by vibrations of atoms and a higher temperature would cause more random thermal fluctuations. Some of these thermal fluctuations have enough energy to throw the photodiode off its metastable state also, causing misfiring.
+
# Temperature is a measure of the size of the vibrations of atoms in a solid. It also reflects the random motion of electrons in the space between the atoms. A higher temperature means larger random thermal fluctuations. A higher temperature also means that there is more chance for electrons to jump to a higher quantum state. Some of these thermal fluctuations have enough energy to create a electron-hole pair and release the photodiode from its metastable state similar, and produce a pulse similar to what is created by a photon. The current generated by thermal avalanches is known as dark current because it is present even in the dark.
390

edits

Navigation menu