Comprhensive Study of P-N Junction

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  • Topic: Semiconductor, Semiconductors, Diode
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  • Published : July 3, 2012
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Dept. of Electrical and Electronic Engineering
Course no.: EEE 2103
Name of the Paper:
Submitted to:
Mr. Md. Ziaur Rahman
Submitted by:
Shafa Al Shahid
Abdullah al Rumi
Md. Shadman Khan (
Reaz Ahmed
Saidur Rahman Mishu (
Date of submission: 28.06.2012

Comprehensive Study On P-N Junction Diode
Shafa Al Shahid , Abdullah al Rumi, Md. Shadman Khan, Reaz Ahmed, Saidur Rahman Mishu
Depertment Of EEE, Ahsanullah University Of Science & Technology, Dhaka, Bangladesh. E-mail of corresponding author:,

Abstract: This paper entitled as “Comprehensive study of p-n junction” includes the following topics – What is semiconductor, Band diagram of semiconductor, Fermi energy level in semiconductors, Intrinsic and Extrinsic Materials, Doping, P-type and N-type semiconductors, Donor acceptor, Majority and Minority carrier, Mobility and Conductivity, Drift and Diffusion current, Ideal p-n junction current.

In the field of electronics, Semiconductor devices are of great importance. In the racing world electronics is the key element of development. And in semiconductor physics, PN junction is way more important than anything else. The comprehensive study of PN junction is given below.

1.Semiconductor :

A semi-conductor is a solid whose electrical conductivity is in between that of a conductor and that of an insulator,and can be controls over a wide range, either permanently or dynamically by changing –

1. Temperature
2. Optical excitations
3. Adding impurity contents


#A semi-conductor is neither a good insulator nor a good conductor of electric current. #Solid semiconductors can exist in the crystalline or amorphous form. #Semi-conductors can crystallize in the diamond,zinc blande or other structures. #The bonding between atoms in a semi-conductor can be covalent,ionic or mixed. #The forbidden energy band in semi-conductors lies between 0.2 eV to 2.5 eV.

* Integrated circuits (ICs) SSI, MSI, LSI, and VLSI.
* Fluorescent materials used in TV screens II-VI (ZnS).
* Light detectors InSb, CdSe, PbTe, HgCdTe.
* Infrared and nuclear radiation detectors Si and Ge.
* Gunn diode (microwave device) GaAs, InP.
* Semiconductor LASERs GaAs, AlGaAs.

1.Based on purity.
* Intrinsic
* Extrinsic.
*P- type
*N- type
2.Based on Band gap.
*Direct Band gap semiconductor.
*Indirect band gap semiconductor.
3.Elementary semiconductor.
Example: Si, Ge.
4. Compound semiconductor.
5. Alloys.
*Binary: GaAs.
*Ternary: GaInP
*Quaternary: GaAsInP

2.Band diagrams of semiconductors
The energy band diagrams of semiconductors are rather complex. The detailed energy band diagrams of germanium, silicon and gallium arsenide are shown in Figure . The energy is plotted as a function of the wavenumber, k, along the main crystallographic directions in the crystal, since the band diagram depends on the direction in the crystal. The energy band diagrams contain multiple completely-filled and completely-empty bands. In addition, there are multiple partially-filled band. Simple energy band diagram of a semiconductor The energy band diagrams shown in the previous section are frequently simplified when analyzing semiconductor devices. Since the electronic properties of a semiconductor are dominated by the highest partially empty band and the lowest partially filled band, it is often sufficient to only consider those bands. This leads to a simplified energy band diagram for semiconductors as shown in Figure

Fig 01: A Simplified Energy Band Diagram.
Figure.01:A simplified energy band diagram used to describe semiconductors. Shown are the valence and conduction band as indicated by the valence band edge, Ev, and the...
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