Physics > Semi-conductor Devices and Electronics > 1.0 Introduction
Semi-conductor Devices and Electronics
1.0 Introduction
1.1 Classification of solids on the basis of their conductivity
1.2 Band theory of solids
1.3 Classification of solids on the basis of band theory
2.0 Types of semiconductor
3.0 Mass action law
4.0 Electrical conductivity in semiconductor
5.0 $p-n$ junction
5.1 Depletion region
5.2 Forward biasing of a $p-n$ junction
5.3 Reverse biasing of a $p-n$ junction
6.0 Breakdown voltage
7.0 $I-V$ characteristics of a $p-n$ junction
8.0 Rectifier
8.1 Half wave rectifier
8.2 Full wave rectifier
8.3 Ripple frequency
8.4 Ripple factor
8.5 Ripple efficiency $\left( \eta \right)$
8.6 Form factor
9.0 Light emitting diode (LED)
10.0 Zener diode
11.0 Transistor
12.0 Boolean identities
13.0 Logic gates
14.0 De Morgan's theorem
1.2 Band theory of solids
1.2 Band theory of solids
1.3 Classification of solids on the basis of band theory
5.2 Forward biasing of a $p-n$ junction
5.3 Reverse biasing of a $p-n$ junction
8.2 Full wave rectifier
8.3 Ripple frequency
8.4 Ripple factor
8.5 Ripple efficiency $\left( \eta \right)$
8.6 Form factor
A. Valence band
This band contains valence electrons. This band may be partially or completely filled with electrons.
This band is never empty. Electrons in this band do not contribute to electric current.
B. Conduction band
In this band, electrons are rarely present.
This band is either empty or partially filled.
Electrons in the conduction band are known as free electrons.
Free electrons contribute to the electric current.
In this band, electrons are rarely present.
This band is either empty or partially filled.
Electrons in the conduction band are known as free electrons.
Free electrons contribute to the electric current.
C. Forbidden band
Forbidden band is often called as forbidden energy gap.
The energy gap between the valence band and conduction band is known as forbidden energy gap or forbidden band.
No electrons are present in this gap. It is a measure of energy band gap.
It is represented by ${E_g}$.
The minimum energy required for shifting electrons from valence band to conduction band is known as energy band gap.
If $\lambda $ is the wavelength of radiation used in shifting the electron from valence band to conduction band, then the energy band gap is given by,
$${E_g} = \frac{{hc}}{\lambda }\quad {\text{or}}\quad {E_g} = h\upsilon $$
where,
$h = 6.63 \times {10^{ - 34}}\;Js$: Planck's constant
$c$: Speed of light
$\upsilon $: Frequency of radiation
$\lambda $: Wavelength of radiation
Relation between forbidden energy gap $\left( {{E_g}} \right)$ and temperature in a semiconductor
For silicon, $${E_g}(T) = 1.21 - 3.60 \times {10^{ - 4}}T$$
At room temperature $(300K)$, ${E_g} = 1.1\;eV$
For germanium, $${E_g}(T) = 0.785 - 2.23 \times {10^{ - 4}}T$$
At room temperature $(300K)$, ${E_g} = 0.72\;eV$
Forbidden band is often called as forbidden energy gap.
The energy gap between the valence band and conduction band is known as forbidden energy gap or forbidden band.
No electrons are present in this gap. It is a measure of energy band gap.
It is represented by ${E_g}$.
The minimum energy required for shifting electrons from valence band to conduction band is known as energy band gap.
If $\lambda $ is the wavelength of radiation used in shifting the electron from valence band to conduction band, then the energy band gap is given by,
$${E_g} = \frac{{hc}}{\lambda }\quad {\text{or}}\quad {E_g} = h\upsilon $$
where,
$h = 6.63 \times {10^{ - 34}}\;Js$: Planck's constant
$c$: Speed of light
$\upsilon $: Frequency of radiation
$\lambda $: Wavelength of radiation
Relation between forbidden energy gap $\left( {{E_g}} \right)$ and temperature in a semiconductor
For silicon, $${E_g}(T) = 1.21 - 3.60 \times {10^{ - 4}}T$$
At room temperature $(300K)$, ${E_g} = 1.1\;eV$
For germanium, $${E_g}(T) = 0.785 - 2.23 \times {10^{ - 4}}T$$
At room temperature $(300K)$, ${E_g} = 0.72\;eV$
