Skip to main content

Biasing of p–n Junction | Forward and Reverse-biased |

Biasing the p-n junction means applying some external voltage to both sides of the p-n junction. Reverse-biased junction and forward-biased junction are two types of biased junction. You should have also good understanding of  N-Type and P-Type Semiconductor before moving towards this topic.

Introduction Biasing of p–n Junction

Biasing of p–n Junction 

Biasing of a p–n junction means uses of some external voltage across the two sides of the p–n
junction. It is divided into two groups 

  1. Forward-biased junction : When the p-side of junction  is connected to the positive terminal of a battery and the n-side of junction is connected to the negative terminal, the p–n junction is said to be a forward-biased junction. 
  2. Reverse-biased junction :If the positive terminal of the battery is connected to the n-side of junction and the negative terminal on the p-side, the p–n junction is said to be a reverse-biased junction.
Now we will see about forward and reverse-biased junction in detail. 


A forward-biased p–n junction

Given figure below shows that the p-side is connected to the positive terminal and the n-side is connected to the negative terminal of a battery .Holes on the p-side are positively charged and the electrons on the n-side are negatively charged.

Forward-biased p–n junction diagram
Forward-biased p–n junction diagram
                                        

  • When forward biased, the positive terminal of the battery will repel the holes from the terminal.
  • Similarly, the electrons on the n side will be repelled from the negative terminal of the battery.
  • As a result, the width of the depletion layer will be reduced. The potential barrier will also get reduced.
  • If the applied voltage is gradually increased, the depletion region and resistor capacitance will disappear. 

A reverse-biased p–n junction

As we know In reverse reverse-biased p–n junction, connection  of  battery is reversed, i.e., the negative terminal of the battery is connected to the p-side and the positive terminal is connected to the n-side of the p–n junction as shown in given figure below :

reverse-biased p–n junction diagram
Reverse-biased p–n junction diagram
 
  • In a reverse-biased p–n junction the electrons on the n-side are attracted to the positive terminal of the battery and the holes on the p-side are attracted to the negative terminal of the battery.
  • In a reverse-biased p–n junction the holes on the p-side are attracted to the negative terminal of battery and the electrons on the n-side are attracted to the positive terminal of the battery.
  • Furthermore, the depletion layer widens as the applied voltage gradually increases.
  • Barrier is reduced to zero because the barrier voltage also gets gradually increased and as such the possibility of the majority charge carriers crossing the barrier.
  • Due to minority charge carriers a negligibly small current of the order of micro amperes will flow that is shown in given figure.
         

From Biasing of p–n Junction we can make the following statements.

Summary of this topic can be memorized by the following statements given below:

  1. A p–n junction is forward biased if its p-side is connected to the positive terminal of the supply and n-side is connected to the negative terminal of the supply.
  2. Barrier potential for germanium is 0.3 V and for silicon is 0.7 V at room temperature. These are the voltage drops across the p–n junction when current flows.
  3. The majority charge carriers current is established in a forward-biased p–n junction.
  4. When p-side is connected to the negative terminal and n-side is connected to the positive terminal of the supply, the p–n junction is said to be reverse biased.
  5. The depletion layer width gets narrowed down on application of forward voltage. 
  6. The width of the depletion layer, and hence the barrier potential increases when the junction is reverse biased.
  7. A forward-biased p–n junction offers very small resistance to current fl ow while a reverse biased p–n junction offers very high resistance to current flow.
  8. A minutely small current flows through a reverse-biased p–n junction due to the minority charge carriers.

Conclusion 

This information about biasing of p–n Junction, biasing of  forward p-n junction and biasing of reverse-biased p-n junction will help you to enhance your knowledge. If you have any question related to this topic then you can comment us.

Comments

Popular posts from this blog

About N-Type and P-Type Semiconductor | Materials | Example |

Here you will know about  n type and p type semiconductor in details. You can already see about bonding in semiconductor . N type and P type semiconductor is used in electronic appliances.which is the basis of working of all the electronic devices.So lets discuss in this given topic in the details. N type and P Type Semiconductor When some impurities added to the pure semiconductor then it becomes extrinsic semiconductor and this process of adding impurities is known as doping.  Now it depends on the which type of impurities it added to the semiconductor (two types of impurities can be added to semiconductor pentavalent or trivalent). n-type semiconductor : If impurity that is added to the pure semiconductor is a pentavalent ( which has five valance electron ) then it is called n-type semi conductor. p-type semiconductor : If trivalent impurity is added to the semiconductor then it becomes p-type semi conductor. ( Note-List of  n type and p type semiconductor material is given below.

Engineers Files Explained | Types of file

Today we will learn about engineers files explained, as we know hand tools are used to remove small amounts of material, usually from small areas of the workpiece.   Do you know why hand tools are used ?Hand tools are used because of following reason: If no machine is available,  The workpiece is too large to go on a machine  The shape is too intricate or simply that it would be too expensive to set up a machine to do the work. As you know the necessity of a hand tools now we will know about a hand tool , engineer's files. Engineer’s files Files are used to perform a variety of tasks, from simple removal of sharp edges to producing complex shapes where use of the device is impractical.Files can be obtained in a variety of shapes and in lengths from 150 mm to 350 mm. Single-cut file: When a file has a single series of teeth cut across its face it is called  single-cut file ,Figure of single-cut file is shown below. double-cut file: When a file has double series of teeth cut across