[introduction] itself their effect is very little, told be neuter popularly, but when these 2 kinds of material are united in wedlock together, can become magical, their behavior kind will be exceedingly different, can arise ” PN writtens guarantee ” thing.

N material and the union that P profile expects form diode, can form PN tie, be so how form?
 
Silicon is impure when a few antimony, it is N semiconductor material, adulterate when silicon material when a few boron, can form P semiconductor material.
 
Itself their effect is very little, told be neuter popularly, but when these 2 kinds of material are united in wedlock together, can become magical, their behavior kind will be exceedingly different, can arise ” PN writtens guarantee ” thing.
 
When they are united in wedlock together, can produce a flight of stairs of very big density, it is a few free electron begin almsgiver impurity atomic migratory cross this new the cavity in the P that the tie that form produces anion with fill material.
 
This moment electron has crossed PN to written guarantee shift arrives from N silicon P silicon, stay in negative side those who carry positive electricity offer body ion, the cavity in impurity accepting put oneself in another’s position is migratory cross a knot to enter the area that has a large number of free electron in opposite way.
 
Density of the P that writtens guarantee when the edge charge is being taken the NA fill of negaive electricity, turn into along density of the N of the knot charge positive electrical charge, this process makes a round trip continual moment, when the electronic amount that crosses a knot more charge repel and prevent any more charge flow child cross a knot, eventually, when sufferring electron of body atom repulsion when cavity of almsgiver atom repulsion, occurrence balance position (electrically neutral circumstance) , it is all round knot area generation ” power base ” area.

Because do not have freedom to carry,flow child the position that can keep in presence power base, because of this and the N that are far from a knot model compare with P data phase, knot the area of two side is completely extinct now any more freedom carry stream child. PN writtens guarantee this area all round calls depletion layer now.

Anyhow, PN writtens guarantee the total charge of each side must equal and way is opposite, ability holds neuter charge position, that is to say 2 person the relation is Dp*N A = Dn*N D.

The distance of depletion layer says for now

Because N material lost an electron, p lost hole, n material is opposite at P model became positive electrode. Next, ionic meeting brings about the impurity that writtens guarantee two side exist to build electric field in this area, n side photograph is in positive electricity to press to P side.
 
Present problem is, free charge needs a few additional energy to overcome the obstacle that exists now, make its can cross extinct area knot.
 
Diffuse the electric field that the process produces produced on node ” inside buy voltage ” , its open a way (0 slant buy) potential is:

PN knot potential

Among them: E O is 0 slant buy knot voltage, v T is the hot voltage of the 26mV below room temperature, n D and N A are foreign matter chroma, n I is to ask for chroma originally.
 
Be in normally below the circumstance, the voltage of two end is silicon depletion layer about 0.7 bend over of 0.6 –, germanium is 0.3 – about 0.35 bend over. Although equipment did not receive any exterior power source repeatedly, base of this kind of power also will exist from beginning to end.
 
So in the theory that writtens guarantee in PN, the semiconductor material that can adulterate through will differring joins or diffuse together to make PN written guarantee, call the electronic device of diode in order to produce, this diode can use the basic semiconductor structure that makes rectifier, all type transistor, LED, solar battery and more equipment of this kind of solid state.

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