Semiconductor Devices
By
Md.Rabius Sani
Biplob Sarker
Fahmida Hossain
Bappy Das
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●Introduction●Types of Semiconductor Devices●Diode●Forward & Reverse Bias●Transistor●Types of transistors●Queries
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Introduction●Semiconductor:●Unit which consists lagely or wholly,of semiconductor materials which can perform useful function in electronic apparatus & solid state research.●Ex:p-n jun diode,transistros,IC's and etc.
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Types of Semiconductors
●There are two types of Semiconductors● 1)Intrisic Semiconductors● 2)Extrinsic Semiconductors●Intrinsic Semiconductors:Tetravalent● Ex:Si,Ge etc●Extrinsic Semiconductors:
Ex:p-type and n-type
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DIODE
●Diode is device with two electrodes.●A p-n juncion diode is a two terminal device made up of semiconductor crystal.●P-N junction diode
+ -
P-n junction diode ckt symbol
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Forward Bias
●Resistance is very small
+ - mADepletion Layer
B
p n
P-n junction-Forward Bias
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Reverse Bias●Resistance is very high●Conduction is due to thermal agitation.
Depletion Layer
B
+-
p n
MA
P-n junction-Reverse Bias
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Transistors●Invented in 1948●A transistor is a semiconductor device used to amplify and switch electronic signal.●Consist of two p-n junctions back to back●Has three regions:●1)Emitter●2)Base●3)Collector
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●Base is made up of P-type●Current conduction is mainly due to holes
P-N-P Transistor
ppp pn
Ckt symbol of p-n-p transistor
E
B
C
p-n-p transistor
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N-P-N Transistor
●Base is made up of p-type.●Current conduction is mainly due to electrons.
E C
B
n npCkt symbol of n-p-n transistor
n-p-n transistor
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Advantages●Used in microcircuits.●They're quite strong&sturdy.●Usually,they've long life.●Swithches turn on&off with the use of transistor.
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ANY QURIES?
●Can two diodes combined back to back as shown in●fig to form a transistor?
P N N P
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THANK YOU
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