Fotorivelatori
1) external photoelectric Effect or emission searchlight:
The energy of the photon is had in the case that illuminates the surface of the material sufficiently is elevated to tear it to the same material and to render it free in the empty one, such effect comes used in the fototubi that is of the tubes to empty in which a cathode it emits electrons that attracted from an electric field current gives to place to one.
2) inner photoelectric Effect or fotoconducibilità :
It is introduced inversely in the polarized splices which in the region of load space introduce them an elevated electric field in a position to separating the charges that come formed from the photon incident on the same region.
3) Largenesses that characterize a fotodiodo:
to) the quantica efficiency h it is the relationship between the flow of charges generated for absorption and the optical power incident.
b) the responsività R given from the relationship between the fotocorrente and the optical power incident
The relation between the two largenesses is 
.
4) Criteria of massimizzazione of the quantica efficiency:
to) it is necessary to diminish the reflections of the surface incident that non-reflecting layer of silice is possible dealing the surface with one
b) to maximize the absorption of the layer emptied expanding of the how many possible dimensions
c) to avoid the recombination
goddesses bearers fotoeccita to you nella emptying region, that
obtains if the relation 
is verified where W1 is the distance between the
surface of incidence and the beginning della emptied zone.
5) Diode valve PIN:
Draft of a splice pn with frapposta an intrinsic region that to the typical polarizations completely is emptied and therefore in it is present an elevated electric field who separates the charges.
6) Schottky Diode valve:
It is a splice constituted from a metal and a semiconductor n-doped, comes used because it eliminates the superficial recombination.
7) fotorivelatori Diode valves to eterostruttura:
The bearers present in the layer are mostly emptied to gap tightened where there is an elevated electric field, and therefore are here that the separation of the charges happens.
8) APD:
Draft of a fotodiodo that it takes advantage of the effect avalanche so as to to associate more bearers to an only photon incident, the goodness of the device is tied to the ability to render the zone very small where effectively effect is had avalanche.
9) microplasma Effect:
In presence of some points where it is had a local elevation of the electric field can be had a premature avalanche in the case the multiplication process does not happen in uniform way on all the illuminated area.
10) Ionization from impact:
When the kinetic energy of a bearer is advanced to the gap, the possibility that exists the bearer yields its energy to an electron in valence band carrying it in conduction band where therefore they are come to having two free electrons while also one has been formed gap in valence band.
11) Coefficient of ionization:
It is the probability that the bearer excites a brace electron-gap, is had toand for electrons and toh for gaps, if the two probabilities are almost equal, both the bearers can ionizzare and therefore the avalanche is caught up quickly also on one ended distance.
12) Coefficient of theoretical multiplication:
13) Coefficient of multiplication experiences them:
14) Defects of the fotorivelatori to the germanium:
to) high currents of buio
b) difficult superficial passivazione
c) the avalanche is begun from the mistaken type of bearers
