Special diode valves
1) Gunn Diode valve:
High one is a used diode valve in order to create impulses to frequency much is constituted from a semiconductor of type n realized con GaAs with the cathode to mass and the anode fed by means of a variable resistance, by means of a condenser captures the escape impulses here. The GaAs is a semiconductor with a gap direct and a gap indirect of second value more elevated therefore to of the electric field that we apply we have two various mobilities therefore two various conductivities in particular to growing of the field and diminishes the conductivity in how much increases the mass effective.
We suppose that they are come to create two distributions of loads positive parallels, they damage place to 2 local electric fields of which a sum to the external field that is next to the critical field and the other is embezzled is had therefore as an example that the electrons are more discs of a valve than those behind, creates a stopper that gives place to an impulse.
2) Laps:
Draft of a condenser MOS in which it comes created the emptying region, the photon that records on it gives to place to a brace electron-gap that comes endured separated from the field giving place to a current impulse that comes captured from the side of the metal by means of a condenser.
3) Fotodiodo:
Draft of a polarized splice PN inversely, the equation is 
in photon absence has the current of buio that it
is negative, if instead they record of photons, must be added one
currentthe S to the current of
buio in particular the intensity of this current is maximum if the
photon hits just in correspondence of the splice and diminishes going
away of this because it increases the probability that the created
minority bearer recombines itself before catching up the splice.
Splice PN is realized with a region p much thin one, the
currentthe S that is obtained is 
4) Diode valve Tunnel:
Draft of a splice PN in which both the regions are many drug addicts, in such a way the region of loads spaces them is infinitesimal, some nm, and therefore you it can be electron passage for effect Tunnel however sbisogna to hold account that the electrons to which that it is allowed are those comprised between the level of Firm and the band of valence of the n_doped and can only make a jump to constant energy towards gaps comprised between the band of valence and the level of Firm of the p_doped. It is had that polarizing inversely the two bands they are not overlapped while polarizing directly can be arrived to having the maximum of the superimposition.
The characteristic of the diodo introduces a feature to negative slope therefore to resistance differentiates them negative that comes used in order to realize the 3 typology of oscillator:
to) monostabile the straight one of cargo intersects the characteristic in a feature to positive slope
b) bistabile the straight one of cargo intersects the characteristic in 3 points of which only those on the features of the characteristic to positive slope corresponds to the stable equilibrium.
c) astabile the straight one of cargo meets the characteristic on the feature to negative slope.
5) Diode valve resonant Tunnel:
It is constituted from alternated GaAs to AlGaAs must be made so that there is an only state available and that is obtained acting on the distance.
6) Led Diode valve:
Draft of a splice PN realized with a semiconductor to gap directed like the GaAs, polarizing directly has an electron passage from the band of conduction to the band of valence with consequent having photon emission accidental phase therefore obtains one source of incoherent light.