PPT: Semiconductors in Electronic Device | Electronic Devices - Electronics and Communication Engineering (ECE) PDF Download

 Page 1


ELECTRONIC DEVICES
Page 2


ELECTRONIC DEVICES
2
UNIT I  - INTRODUCTION TO SEMICONDUCTOR PHYSICS
AtomicStructure:
? Atomic structure refers to the structure of atom comprising of a nucleus (center) 
in which the protons (positively charged) and neutrons (neutral) are present.
? The negatively charged particles called electrons revolve around the center of 
the nucleus.
Protons (positively charged), neutrons(neutral), Electrons 
(Negatively charged)  
Atomic weight = no of protons + no of neutrons.
Atomic number = no of protons / no of electrons in atom
Page 3


ELECTRONIC DEVICES
2
UNIT I  - INTRODUCTION TO SEMICONDUCTOR PHYSICS
AtomicStructure:
? Atomic structure refers to the structure of atom comprising of a nucleus (center) 
in which the protons (positively charged) and neutrons (neutral) are present.
? The negatively charged particles called electrons revolve around the center of 
the nucleus.
Protons (positively charged), neutrons(neutral), Electrons 
(Negatively charged)  
Atomic weight = no of protons + no of neutrons.
Atomic number = no of protons / no of electrons in atom
4
Energy band description
? Bands are classified into 2 types
1.Valance Band 
energy possessed by valence electron.
2. Conduction band:
energy possessed by free electron.
3. Forbidden energy gap:
Separation between conduction band and  valance band on the energy 
level diagram.
Page 4


ELECTRONIC DEVICES
2
UNIT I  - INTRODUCTION TO SEMICONDUCTOR PHYSICS
AtomicStructure:
? Atomic structure refers to the structure of atom comprising of a nucleus (center) 
in which the protons (positively charged) and neutrons (neutral) are present.
? The negatively charged particles called electrons revolve around the center of 
the nucleus.
Protons (positively charged), neutrons(neutral), Electrons 
(Negatively charged)  
Atomic weight = no of protons + no of neutrons.
Atomic number = no of protons / no of electrons in atom
4
Energy band description
? Bands are classified into 2 types
1.Valance Band 
energy possessed by valence electron.
2. Conduction band:
energy possessed by free electron.
3. Forbidden energy gap:
Separation between conduction band and  valance band on the energy 
level diagram.
5
Classification of Solids
? Classification based on:
1.valance electrons  
2.Free electrons  
3.Forbidden energy gap
? Valance electron: determines the metal, non-metal, solids, gas, and 
electrical  properties of a material based on outermost valance electron.
? Electrical conductivity of material are classified into
• conductor  
• insulator
• semi-conductor
? Free Electrons valance electrons which are Loosely attached to the
nucleus
Page 5


ELECTRONIC DEVICES
2
UNIT I  - INTRODUCTION TO SEMICONDUCTOR PHYSICS
AtomicStructure:
? Atomic structure refers to the structure of atom comprising of a nucleus (center) 
in which the protons (positively charged) and neutrons (neutral) are present.
? The negatively charged particles called electrons revolve around the center of 
the nucleus.
Protons (positively charged), neutrons(neutral), Electrons 
(Negatively charged)  
Atomic weight = no of protons + no of neutrons.
Atomic number = no of protons / no of electrons in atom
4
Energy band description
? Bands are classified into 2 types
1.Valance Band 
energy possessed by valence electron.
2. Conduction band:
energy possessed by free electron.
3. Forbidden energy gap:
Separation between conduction band and  valance band on the energy 
level diagram.
5
Classification of Solids
? Classification based on:
1.valance electrons  
2.Free electrons  
3.Forbidden energy gap
? Valance electron: determines the metal, non-metal, solids, gas, and 
electrical  properties of a material based on outermost valance electron.
? Electrical conductivity of material are classified into
• conductor  
• insulator
• semi-conductor
? Free Electrons valance electrons which are Loosely attached to the
nucleus
6
Classification of Solids
Conductor
? It is a material that easily conducts electrical 
current.
? It has large number of free electrons loosely 
bound to the atoms.
? These loosely bound valance electrons can 
easily break away from their atoms and 
become free electrons.  
? Forbidden energy gap does not exist.
? Examples : Copper, Gold, Silver