Wednesday 6 May 2015

Basic concept of : semiconductor Diode

1 - Semiconductors

1.1 - What are Semiconductors?
Matter
semiconductor materials to produce various kinds of semiconductor devices such as
Diodes, transistors, IC, which I had seen in the electronics Day
today.

Semiconductors are substances with characteristics intermediate between
conductors and insulators, in chemical terms, the semiconductor is
4 E substances in the outermost layer of atoms. That is the nature
Germanium (Ge) and silicium (Si)

From the initial semiconductor (pure) one must
create two types of semiconductor transistors are N-type and P-type semiconductors, then
puzzle pieces N and P type semiconductors obtained the diode or transistor.

Si and Ge are 4 valence, ie the outermost layer 4
e, can in pure Si atoms (Ge) linked together
covalent links shown below.

Pure semiconductors.


1.2 - Semiconductors Category N

* When you mix a small amount of chemotherapy with 5 as phosphorus (P) in nature
Semiconductor silicon atom is linked to 4 P Si atom by association
covalent, only 4 atoms of phosphorus electron involved in affiliate
and residual electron and become a free electron => Semiconductors time
became redundant electronic (negatively charged) and semiconductors called N (
Negative: negative).

Semiconductors N

1 .3 - Semiconductors Category P


Conversely, when we added a small amount of chemotherapy with 3 as Indium
(In) in the first semiconductor Si atoms will link Indium
with 4 Si atoms according covalent link and link missing
E => become holes (positively charged) and is
semiconductors called P.

Semiconductors P


2 - Diode (LED) Semiconductor

2.1 - Contiguous P - N and structure of semiconductor diode.
At
had been two semiconductors are P and N, if two semiconductor compound according to
an adjacent P - N It is a diode, adjacent P characterized -N
: In the contact surface, the excess electrons in the semiconductor N diffusers
to the semiconductor P to fill the holes => forms a layer Ion
neutral electricity => Ion class domain constitutes insulation between
two semiconductor.

Contacts P - N => Diode Configuration.

* In the image on the contacts P - N and also the structure of the semiconductor diode.



Symbols and shape of the semiconductor diode.


2.2 - Sub-biased for the diode.
At
our positive voltage (+) to anode (the semiconductor P) and negative voltage (-)
in Katot (semiconductor region N), while under the effect of electric interactions
pressure, shrinking domain insulator when the voltage reaches the gap between the two poles
0,6V (with diode type Si) or 0,2V (with diode type Ge), the area
domain area Insulation reduces zero => Diode start conductivity. If
continue to increase the voltage source, a current through the diode increases rapidly but differences
voltage difference between the poles of diode does not increase (remain 0,6V)


Diode (Si) biased - When Dode guide
gim upon current voltage at 0,6V

Curve of forward voltage across the diode


* Conclusion: When Diode (type Si)
is biased, if bias voltage <0,6V is no
Diode line passing, if biased voltage gain = 0,6V then crossing the line
Diode then current through the diode voltage drop upon increasing but remains
in value 0,6V.
2.3 - for Diode Reverse Polarity.


When the diode reverse polarity power supply means (+) in Katot (sold
guide N), source (-) to anode (semiconductor P), under voltage interaction
in contrast, the wider region and insulated to prevent electrical current through
contiguity, the diode can withstand reverse voltages very large
about 1000V, the new diode is punctured.

Diode only fires when the reverse bias voltage increases> = 1000V

2.4 - Measurement methods test Diode


Measure check Diode




  • Set in an elevator x 1Ω clock, put two strips at the ends Diode, if:


  • Conveniently measuring rods into anode black, red rods in Katot => needle up, reversing the needle does not measure up is => Diode good


  • If measuring both clockwise up = 0Ω => was short-Diode.


  • If the needle does not measure up positively => Diode is broken.


  • In the diode D1 measurements on good, diode D2 and D3 short-cuts


  • If that measure to scale back into diode 1KΩ metal is still up a little diode detectors.

2.5 - Application of semiconductor diode.


* Due to the one-dimensional conductors should Diode
often used in the rectifier into an AC source
dimensional detector circuits, circuit bias gim for transistor operation
action. in rectifier diode can be integrated into a diode bridge
form.


Diode rectifier bridge in AC.


3 - Types Diode

3.1 - Zener Diode
* Components:
Zener diode has a structure similar to the diode normally but there are two layers of semiconductor P
- N coupled together, Zener Diode applied in polarization mode
in contrast, when the forward bias diode zener diode as often but when feces
gim zener diode will reverse bias voltage to a fixed value
recorded on diode.

Shape Zener diode (Dz)


Symbols and applications of zener diode in the circuit.




  • The diagram above illustrates the application of Dz, source voltage source U1 is changed, voltage regulator diode Dz, R1 is becoming limited line.


  • We see that the source U1> Dz Dz, shall always fixed on whether sources U1 change.


  • When sources U1 change the line back through Dz change, reverse flow through Dz limit value of about 30mA.


  • Usually people use source U1> 1.5 => 2
    Dz and installation times or R1 current limit so that the largest reverse flow through Dz
    <30mA.



If U1 <Dz when pressure on Dz U1 change also changes
If U1> Dz when U1 change => constant pressure on Dz.
3.2 - Thu optical diode. (Photo Diode)
Diode
optical receiver operate in reverse polarity mode, with a piece of bark diode
glass to light in connection P - N, reverse current through the diode
proportional to the intensity of light falling on diode.

Symbol of Photo Diode


Illustrating the operation of Photo Diode


3.3 - Luminescence Diode (Light Emiting Diode: LED)
Diode
development phang light emitting diode is being biased, voltages
Work of LED 1.7 => 2,2V line ranges from 5mA to pass Led
20mA

Led used to make light sources, decorative flashlight, power status. etc ...

LED light emitting diode


3.4 - Diode varicap (variable capacitance diode)
Diode variable capacitance diode capacitance is like capacitor, and the capacitance change when we change put into diode reverse voltage.


What variables into applications of diode varicap (V D)
the resonant circuit


  • In the picture above when we adjust VR dimmable voltage
    Diode varicap placed opposite change of diode capacitance change
    => Changed the resonance frequency of the circuit.


  • Variable capacitance diode is used in the color television channel, in the tuned circuit resonant frequency by voltage.

3.5 - Diode pulse
In
the source of the output pulse of the pulse transformer, we must use Diode
pulses to the rectifier. pulse diode diode is working at high frequencies of several
tens of KHz, conventional diode rectifier irreplaceable position
pulse diode, but backward pulse diode can substitute for location
ordinary diode, diode pulse diode costs often many times higher.

Feature, Diode pulse shape is not any different with Diode
Often, however, the pulse Diode often dashed mark or ring
marked by two rounds

Symbol of pulsed Diode

3.6 - Diode detector.


A type of small notebooks glass diode and diode contacts called for
the contact surface between the semiconductor P - N at a point to avoid electricity
parasitic capacitance, diode detector used in high-frequency circuits
to separate the signal wave.
3.7 - Diode adapter.


Diode is to face adapter used in the rectifier AC 50Hz
, This diode is usually 3 types 1A, 2A and 5A.

Diode 5A adapter

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