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Carrier Diffusion, Generation and Recombination in Semiconductor Devices
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Carrier Diffusion, Generation and Recombination in Semiconductor Devices

Understanding how diffusion, generation and recombination drive charge transport in a semiconductor.

Vikram Sekar's avatar
Vikram Sekar
May 04, 2025
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Vik's Newsletter
Vik's Newsletter
Carrier Diffusion, Generation and Recombination in Semiconductor Devices
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This article is part of The Joy of Semiconductor Devices series — a collection of posts that explains the inner workings of semiconductor technology from first principles in an accessible manner.


Here are the previous posts in this series if you need to refer back to the concepts used in this article:

Understanding Energy Bands in Semiconductors

Understanding Energy Bands in Semiconductors

Vikram Sekar
·
Jan 26
Read full story
Semiconductor Doping, Electron Affinity, Work Function and Anderson's Rule

Semiconductor Doping, Electron Affinity, Work Function and Anderson's Rule

Vikram Sekar
·
Feb 2
Read full story
How Electrons Move in Semiconductors: The Science of Carrier Drift

How Electrons Move in Semiconductors: The Science of Carrier Drift

Vikram Sekar
·
Mar 23
Read full story

Earlier, we looked at how electrons drift in a semiconductor when an electric field is applied to it. Today, we will look at another mechanism of charge transport called carrier diffusion, discuss generation and recombination, and bring it all together with the continuity equation.

Here is what we will cover:

  • Mechanism of Carrier Diffusion: How charged particles in a semiconductor move due to diffusion.

  • Diffusivity and the Diffusion Equation: Understanding the factors that control the flow of diffusion current.

  • Current Density: Calculating electron and hole current densities due to drift and diffusion.

  • Generation and Recombination Processes: Generation and annihilation of electron-hole pairs and its relation to the energy band diagram.

  • The Continuity Equation: The expression that ties the different charge transport mechanisms together.

Read time: 10 mins


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