This assignment represents the basic information and basicss about the P-N junction rectifying tube and the belongingss of P-N junction capacitance. The experiment shows the formation of P-N junction depletion bed electrical capacity belongingss. This experiment shows the features of depletion bed junction electrical capacity with regard to the peculiar electromotive force. Here we are find out the formation of depletion bed electrical capacity. We calculate the junction bed electrical capacity ( CA ) in assorted belongingss with several to the electromotive force beginning.
Introduction:
This P-N junction rectifying tube is holding some of import features and which is used in many applications in modern electronics. It ‘s holding two semiconducting materials which are farmed by individual Si crystal.
Here P-type semiconducting material is holding trivalent dross and the bulk bearers are holes. N-type semiconducting material is holding pentavalent dross and the bulk bearers are negatrons and both are semiconducting materials, but the junction farmed between them is a nonconduction bed. This junction bed is called as depletion bed. This depletion bed occurs the charged atoms negatrons and holes pull and repel to each other i.e. recombination of each other. In P-N junction rectifying tube flow of current is in merely one way. This can be represented in forward prejudice & A ; contrary prejudice where prejudice indicates application of electric electromotive force to the p-n junction.
The P-N junction rectifying tube features are given by
In P-N junction rectifying tube, there are two types of operations are at that place i.e. forward prejudice and contrary prejudice.
FORWARD BIAS:
V-I features of p-n junction rectifying tube in contrary prejudice status
In Forward-bias instance when the p-type semiconducting material is connected to the positive terminus of a battery and the N-type Si is connected to the negative terminus of a battery. Then negatrons and holes are attracted both pushed to words the depletion bed. Then the depletion bed breadth is decreased i.e. really thin, and the possible and electromotive force are increased so the opposition is decresed.In this instance both negatrons and holes travel in opposite way, besides they have opposite charges so the overall current is in the same way on both sides of the P-N junction rectifying tube.
Rearward prejudice:
In contrary prejudice instance when the p-type semiconducting material is connected to the negative terminus of a battery and the N-type Si is connected to the positive terminus of a battery. Then the holes in the P-type part, negatrons in the n-type part are pulled off from the junction, and so automatically the depletion bed breadth increased. The possible barrier additions greatly so increases the electrical opposition against the flow of charge bearers. So there will no current flow in the rectifying tube.
Depletion bed electrical capacity: –
In P-N junction rectifying tube which is in the contrary prejudice instance the depletion bed breadth increased. Due to the more diffusion of the holes into the n-type part and the negatrons into p-type. In this instance dual depletion bed is formed. Here depletion bed electrical capacity is occur because there will be being of the opposite beds are formed in the p-n junction rectifying tube.
In this power semiconducting material devices is have some parametric quantities i.e. breakdown electromotive force, on opposition, rise and autumn times and thermic opposition.
Theory:
P-N junction semiconducting material devices with the aid of simple dc word pictures of p-n rectifying tube and besides command the control factor, change by reversal impregnation current and the rectifying tube commanding. In this p-n junction rectifying tube we find the junction electrical capacity merely on the ac word picture. Here the frequence response of the depletion bed electrical capacity is called as junction electrical capacity. The p-n junction electrical capacity has categorised in to two i.e. Depletion bed or infinite charge electrical capacity and diffusion electrical capacity. If a p-n junction rectifying tube is biased status at a Dc contrary prejudice and with a minute Ac electromotive force a charge accretion takes topographic point at the border of the dc infinite charge part comes from ionisation or the deionization procedure of both giver and the acceptor dross in the depletion bed electrical capacity. This electrical capacity is straight related to the prejudice electromotive force.
Harmonizing to abrupt theory the depletion bed of a p-n junction can be in the signifier as
Equation ( 1 ) we can besides denoted as
Where V -applied bias electromotive force
V0- contact potency
Equation ( 1 ) we can besides denoted as
The above equation same as the Y=mX+C, so we have to plot the graph between V and 1/Ca2
to same as shown below. Here the given values the country of rectifying tube is 1.27 cm2 and N”r =12
?„o =8.854*10-12 F/M, e=1.6*10-19 C.
Graph: –
The electrical capacity per unit country by utilizing the experiment is given
Where Cmeas -measured Capacitance of the depletion bed
Ccir-circuit electrical capacity of the circuit.
Purpose:
To mensurate the depletion bed electrical capacity of a Si p+ -n rectifying tube as a map of applied prejudice electromotive force, to prove the cogency of the disconnected junction theory.
D C P To mensurate the depletion bed electrical capacity of a Si p+ -n rectifying tube as a map of applied prejudice electromotive force, to prove the cogency of the disconnected junction theory.
ower
supply
Wayne Kerr
Bridge
Dvm
Circuit diagram
Experimental PROCIDURE:
( 1 ) Connect the circuit as shown in above diagram. Before exchanging on the power supply we have to set the minimal end product electromotive force. In contrary prejudice instance the electromotive force does non transcend -30 V.
( 2 ) Take readings of the prejudice electromotive force and the Cmeas values in the instance of contrary prejudice electromotive force is -30 to -2 Vs and we have to take the values from -2V to 0V in the interval of 0.5V.
( 3 ) Then we are take the rectifying tube and take the measurings for assorted prejudice electromotive forces and circuit electrical capacity ( Ccir ) .To convert measured junction electrical capacity Cmeas, and we are find out the value CA.
Precautions:
( 1 ) Avoid the loose connexions, the connexions should set up as per the circuit diagram.
( 2 ) If we get any negative readings we have to alter the connexion of the DVM.This is called parallax mistake.
Consequence:
Here we can happen the values of Cmeas, Ccir with several to voltage and happen the value of 1/CA2. so use the graph and tabular signifier between electromotive force and 1/CA2.
Reverse Bias Voltage ( V )
Junction Capacitance, Cmeans ( F )
CA ( F/m2 )
1/ ( CA ) 2 ( m2/F2 )
D.C Power Supply
Digital Voltage Meter ( DVM )
30
-29.33
6.29E-10
28
-27.49
6.47E-10
26
-25.49
6.70E-10
4.58E-06
24
-23.51
6.93E-10
4.77E-06
22
-21.54
7.19E-10
4.97E-06
20
-19.59
7.49E-10
5.21E-06
18
-17.62
7.84E-10
5.48E-06
16
-15.67
8.25E-10
5.80E-06
14
-13.70
8.73E-10
6.18E-06
12
-11.74
9.33E-10
6.66E-06
10
-9.80
1.00E-09
7.18E-06
8
7.83
1.10E-09
7.97E-06
6
-5.86
1.24E-09
9.07E-06
4
-3.90
1.45E-09
1.07E-05
2
-1.95
1.88E-09
1.41E-05
1.5
-1.45
2.08E-09
1.57E-05
1
-0.96
2.38E-09
1.81E-05
0.5
-0.47
2.90E-09
2.21E-05
0
-0.18
3.48E-09
2.67E-05
Table ( a ) : Junction electrical capacity, Cmeans value with rectifying tube
Reverse Bias Voltage ( V )
Capacitance of the Circuit, Ccir ( F )
D.C Power Supply
Digital Voltage Meter ( DVM )
-30.00
-29.60
8.68E-11
-28.00
-27.66
8.74E-11
-26.00
-25.69
8.74E-11
-24.00
-23.71
8.74E-11
-22.00
-21.73
8.75E-11
A
-20.00
-19.80
8.76E-11
A
-18.00
-17.87
8.77E-11
A
-16.00
-15.81
8.78E-11
A
-14.00
-13.82
8.78E-11
A
-12.00
-11.86
8.78E-11
A
-10.00
-9.86
8.78E-11
A
-8.00
-7.93
8.79E-11
A
-6.00
-5.99
8.79E-11
A
-4.00
-3.99
8.70E-11
-2.00
-1.97
8.75E-11
-1.50
-1.48
8.75E-11
-1.00
-0.99
8.75E-11
-0.50
-0.54
8.75E-11
0.00
-0.07
8.75E-11
Table ( B ) : Junction Capacitance, Ccir value
without rectifying tube
Then we have to stand for the graph shown in below
From the above graph we are find out the value of the incline
m=5.578*10-10
Besides the negative prejudice electromotive force is
V0=1.023 V
We can happen the incline value by utilizing graph we can utilize the below expression
. m ( incline ) = ( Y2-Y1 ) / ( X2-X1 ) = 5.578*10-10
Then we can be find out the value of ND
Harmonizing to equation 2 we can show the incline is
m=
But NA & gt ; & gt ; ND so we are neglected the ND value
Then the above equation is changed as
The resulted ND value ND=6.562*1019
Here V0 is negative bias electromotive force.
Then we are find out the entire depletion bed breadth utilizing below equation
W=
Here VO= 1.08, ND=6.562*1019 atom cm-3
But Na & gt ; & gt ; Nd so the above equation is changed as below
W=
so the entire breadth of the junction depletion bed ( W ) at -30 V is
W=2.508*10-5
After completion of width sum we have to stand for in a tabular array
Reverse Bias Voltage ( -V )
Width ( W )
30.00
2.48E-05
28.00
2.40E-05
26.00
2.31E-05
24.00
2.23E-05
22.00
2.14E-05
20.00
2.04E-05
18.00
1.94E-05
16.00
1.84E-05
14.00
1.73E-05
12.00
1.61E-05
10.00
1.48E-05
8.00
1.34E-05
6.00
1.18E-05
4.00
1.00E-05
2.00
7.80E-06
1.50
7.14E-06
1.00
6.41E-06
0.50
5.59E-06
0.00
4.62E-06
Then the graph between the entire breadth and contrary prejudice electromotive force
We can presume a big contrary prejudice electromotive force in this instance V & gt ; & gt ; V0 so find the value CA at -0.5 contrary prejudice electromotive force
Then the junction depletion bed electrical capacity is
Calcium
Then the value of CA is 1.879*10-5.This value is about equal to the old value of CA the status of equation.
Abrupt junction behaves like a parallel home base capacitance, that ‘s why we can utilize this application in VARACTOR DIODE.Varactor rectifying tube operates in microwave scope. These rectifying tube belongingss are every bit same as the P-N junction rectifying tube. Because it is besides depends on the junction bed electrical capacity which is depends on the electromotive force. This rectifying tube is used in many application i.e. in amplifier it produced really low noice ; it is a basic constituent in a parametric amplifiers.
Decision:
We already know about power semi music director devices. Here we are discussed about the P-N junction depletion part. The disconnected junction theory hold good for the depletion part. Here P-N junction rectifying tube in forward bias the depletion bed breadth increased in contrary prejudice status the depletion bed breadth is decreased, in contrary bias status we are acquiring this depletion bed electrical capacity. All the P-n junction rectifying tube depletion bed electrical capacity consequences and computations are investigated.
