Splices between material semiconductors
1) Relation of Einstein:
2) Equation of Poisson:
3) It upgrades them of Built-In:
Putting to contact a p_doped with a n_doped a travaso is
had of loads for spread, such process comes stopped rebelling of
upgrades them of Built-In 
where nn0 it is the electron concentration in the
region n to the equilibrium while pp0 is the gap concentration in the region
p to the equilibrium.
4) Amplitude of the emptied regions:
Making the approximation of complete emptying and applying
the equation of Poisson 
and in the fattispecie
ha 
e is obtained 
5) Pin Diode valve:
Between the region p and the region n it comes inserted a layer of weakly drugged intrinsic semiconductor or that for whichever applied polarization it completely turns out to be emptied.
6) Typology of alignments for eterostrutture:
Alignment of 1° type has a tightened material to gap that form a hole of upgrades them place to contact with a material to gap wide that forms the barriers is for the conduction band that for the valence band.
Alignment of 2° type with an opportune one chosen of the seemiconduttori materials one of they can act as from hole of upgrades them for electrons and from barrier for gaps.
7) Model of Anderson and Frensley-Kroemer:
In a eterostruttura they come placed to contact
semiconductors with gap various, the model of Anderson previews that
this variation of gap determines one variation of the energy of the
band of equal conduction to the difference of the electronic
affinities 
. Draft of a model that account
of the dipole presence does not hold that is formed because of the
interface, that instead it is previewed in the model of
Frensley-Kroemer for which the discontinuity of the valence band is
given from 
the .
8) realizzative Epitaxy and techniques:
The epitaxy consists in realizing a thin crystalline layer of material semiconductor whose property are determined from the below substrate. The possible techniques are following:
LEC similar to the Czochralsky method
LPE the crystalline layer grows a liquid solution beginning from saturates diluted on a crystalline substrate
VPE the increase process is fed from a vapor and therefore it demands high temperatures
MOCVD is based on the pyrolysis of metallorganici elements in presence of idruri
MBE of makes us molecular comes deposits to you on a heated crystalline substrate
9) Nearly levels of Firm:
In conditions equilibrium does not have an only level of
Firm bensi 2 that come to coincide when the equilibrium is caught up,
have cioè 
e
10) Density of current in the Schockley diode valve:
wherethe s1 it is the saturation current that crosses the splice in the case of inverse polarization.
11) Efficiency of injection electronic:
