Band charts
1) Structure of the Silicon and the Diamond:
In the inner shell of the diamond there are 2 electrons on the level of energy 1s, while according to shell it is constituted from two electrons on the level of energy 2s and others 6 on the level of energy 2p. The silicon then has a third shell constituted from 2 electrons on the state 3s and 2 electrons on the state 3p.
2) energetic Levels of the diamond to diminishing of the reticular parameter:
One is had up that the levels 2s and 2p meet low creating one band of valence constituted from 4N be, band of conduction also it constituted from 4N be and in means one forbidden band. ? to notice that also the level 1s degenerates giving place to of the forbidden bands moreover to the 0K the conduction band it is empty while the valence band is full.
The value of the gap is function of the type of drogaggio of the semiconductor.
3) Factor of Boltzman:
4) Fermi-Dirac Function:
5) Density of states:
6) intrinsic Concentration of electrons and gaps:
to ambient temperature (300K) it is worth 2.5*1019 .
7) Level of Firm:
it is interesting to notice that the level of Firm is found exactly to half of the energy gap in the case that the mass of the gap is equal to the mass of the electron.
8) Energy of Firm in the case of a drugged semiconductor:
it is observed therefore that in the case of drogaggio of type p the level of Firm is moved towards the valence band while in the case of drogaggio of type n the level of Firm is moved towards the conduction band.
9) spread and Equations drift:
10) Relation of Einstein:
11) Effect of the intersection between the Firm level of Firm and the level of intrinsic :
It is had that the region in which the level of Firm intrinsic it finds to the disotto of the level of Firm comes called reversal zone in how much is like if more it were not drugged than type p but of type n.
12) Effect of the intersection between the level of Firm and the band of conduction :
In the region in which the level of Firm it is found over the conduction band it creates the so-called one âgas of elettroniâ? that it renders the semiconductor of all the similar one to a metal.
13) Realization of a band chart:
to) designing it places side by side the energetic levels relati to you to the various materials and to characterize the distances that must remain unchanged in particular in the contact metal semiconductor must remain unchanged energy gap of the semiconductor and the distance of the level of Firm of the metal regarding the band of conduction and to the band of valence of the semiconductor while in the contact between two semiconductors the values of the two energy must remain unchanged gap, the distance between the two bands of conduction and the distance between the two bands of valence.
b) To design the back in which the electrons that is from the material with elevated energy of Firm towards that one with energy of Firm slide more more lowland.
c) Based on the back in which the electrons slide to determine if the bands in material determining are raised or they are lowered, in particular if electrons go away from a type semiconductor n are had that in correspondence of the splice it if of it impoverisce and therefore the level of Firm lowers that is approaches itself that one of an intrinsic semiconductor, having but it to remain firm has itself that the conduction band must go away from it that is to raise itself. Analogous if the electrons flow in the type semiconductor p, it if it enriches some and therefore it is had that the level of Firm approaches that one of an intrinsic semiconductor that is the conduction band goes away from the level of Firm and having it to remain firm, the conduction band is lowered.
d) To design the level of Firm intrinsic always comprised between the band of valence and the band of conduction
and) To characterize the transition region where the bands begin to fold themselves, eventually to its inside the region of Firm reversal that are had when the level of intrinsic intersects the level of Firm, eventually to its inside the region of degeneration in which the band of Firm conduction crosses the level of (…electron gas) or the band of Firm valence crosses the level of (…gap gas).
f) To design the diagram of the density of it loads bringing back the zones identified to the point and) and characterizing the region of transition with it loads fixed positive in the case of a type semiconductor n and negative in the case of a type semiconductor p, while the reversal regions are characterized from loaded furnitures to exponential course finally the degeneration region are much small and characterized from it loads fixed. The metal is had then that for repulsion introduces loads all disposed one on the such faying surface and to render the material totally neutral.
g) To design to the diagram of the electric field bringing back the zones indicated to the point and) and remembering that the electric field is the integral of load for which in the transition region where it is had loads fixed has a straight one, in the reversal region where it is had loads piece of furniture to exponential course, the electric field has also it exponential course and in the region of contact between two various semiconductors having to be respected the conservation of the carrier D movement, a discontinuity of the electric field must be had.
h) To design the diagram of it upgrades bringing back them the zones indicated to the point and) and remembering that she upgrades them is obtained integrating the electric field and cambiandogli of sign therefore in the transition region where the electric field is a straight one, she upgrades them is a parabola while in the reversal region where the electric field is a exponential , upgrades them is also exponential it but with the opposite sign finally in the transition region one is had parabola. It is observed that in the region where the two semiconductors come to contact and therefore it has a discontinuity of the electric field, must be had also a discontinuity of upgrades them.
14) Calcolo of the function job of a material:
The function job qf measure the distance in eV between the empty level of and0 and the level of Firm of a
material, it depends on the physical characteristics of the material,
in order to measure it puts the material on a plate of a condenser in
which the distance between the armors it comes made to vary the law
second 
, on the other armor comes place which as an
example a having material famous function job the gold. The
condenser comes excited with one continuum flow while if of ago to
vary the distance between the armors the current that obtains is
sended to the clip negative of an operational one that has the other
end to mass, a tension is obtained that it is proporziona them to the
difference of the functions job and can be calculated by means of a
detector of effective value.