The presentation summarized the Metal Oxide Semiconductor Field Effect Transistor (MOSFET). It described the basic structure of a MOSFET, including the gate, source, drain, field oxide and gate oxide layers. It explained the working principle of a MOSFET, noting that applying a positive or negative gate voltage can invert the p-type semiconductor surface to n-type, controlling the flow of electrons between the source and drain. Finally, it discussed common applications of MOSFETs in electronics like calculators, memory devices, power amplifiers and automobile sound systems.

1. WELCOME TO MY
PRESENTATION

2. 2
Sonargon university
Department of mechanical
Md.Touhid islam
Id:BME1703013073
Sec:whinchat

3. Metal OxideSemiconductor
FET(MOSFET)
3

4. MOSFET
 A MOSFET (Metal Oxide Semiconductor Field Effect Transistor)
is a semiconductor device.
 A MOSFET is most commonly used in the field of power electronics.
 A semiconductor is made of manufactured material that acts neither
like a insulator nor a conductor.
 Types

5. MOSFETStructure
n+
L
Source Gate Drain
Field Oxide
Gate Oxide
p-Si
Bulk (Substrate)
5

6. Schematic structure of
MOSFET

7. Working principle of MOSFET




Theworkingprincipleof MOSFET dependsuponthe
MOS capacitor.
TheMOS capacitoristhemainpart.
Thesemiconductorsurfaceatbelowtheoxidelayerand
betweenthedrainandsourceterminalcanbeinverted
fromp-typeton-typebyapplyingapositiveornegative
gatevoltagesrespectively.
When weapply positive gate voltage the holes present
beneath the oxide layer experience repulsive force and
theholesarepusheddownwardwiththesubstrate

8. Working principle of MOSFET

9. Working principle of MOSFET
The depletion region is populated by the bound negative
charges, which are associated with the acceptor atoms.
The positive voltage also attracts electrons from the n+
source and drain regions in to the channel.
The electron reach channel is formed. Now, if a voltage is
applied between the source and the drain, current flows freely
between the source and drain gate voltage controls the
electrons concentration the channel.
Instead of positive if apply negative voltage a hole channel will
be formed beneath the oxide layer.

10. Basic Operation
Before After
10

11. MOS transistors Symbols
D
S
G
D
G
G
S
G
NMOS Enhancement
D
PMOS
S
NMOS Depletion
D
Enhancement
B
S
NMOS with
Bulk Contact
Channel

12. N and P channel of MOSFET

13. N and P channel of MOSFET
 If the MOSFET is an n-channel or nMOS FET, then the
source and drain are 'n+' regions and the body is a 'p' region.
 If the MOSFET is a p-channel or pMOS FET, then the source
and drain are 'p+' regions and the body is a 'n' region.

14. 8
vGS > Vt ,small vDS
applied.
the channel
conductance
is proportional
to vGS - Vt,
and is
proportional
to (vGS - Vt)
vDSS.eptember 17, 2007
Triode
Region

15. September 17, 2007 9
vGS > Vt.
The induced
channel acquires
a tapered shape
and its
resistance
increases as vDS
is increased.
Saturation
Region

16. September 17, 2007 12
Enhancement-type NMOS transistor operated with vGS > Vt.
Drain current iD versus vDS

17. MOSFET Applications:

MOSFETs are used in digital integrated circuits, such as
microprocessors.
 Used in calculators.
 Used in memories and in logic CMOS gates.
 Used as analog switches.
 MOSFET devices are also applied in audio-frequency
power amplifiers for public address systems

18. MOSFET Applications
• Used as amplifiers.
• Used in the applications of power electronics and switch
mode power supplies.
• MOSFETs are used as oscillators in radio systems.
• Used in automobile sound systems and in sound
reinforcement systems

19. JEFTvsMOSFET
JEFT MOSFET
1. High input impedance 1. Very high input impedance
2. It canbe operated only indepletion
mode.
2. It canbe operated both depletionand
enhancement mode.
3. High gate current 3. Low gate current
4. High drain resistance 4. Low drain resistance
5. Conductivity is controlled bythe
reverse biasing of the gate
5. Conductivity is controlled bythe
carriers induced in the channel
6. Schematic symbol 6. Schematic symbol
7.Transconductance curve 7.Transconductance curve
30

20. Summary of
presentation