SiC Vertical MOSFET channel length modulation

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In summary, the conversation discussed the difference between lateral and vertical MOSFETs and their respective applications. The main difference is that the drain in a vertical MOSFET is located in a different plane from the source and gate, allowing for stronger voltage withstand capabilities. More information about lateral MOSFETs can be found at the provided link.
  • #1
bonkgeek
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Hello , Thank you readind me
I wonder how to represent the reduction in channel length(pinch off seen in lateral MOSFET) for vertical mosfets due to the increase in drain voltage because the drain is at the back, away from the creation of the channel position.
 

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  • #2
Welcome to PF.

Your diagrams only seem to show lateral MOSFETs. Can you show a typical vertical MOSFET geometry and say where it is used? I have not used them yet.
 
  • #3
Thanks
I am presenting a vertical MOSFET, where the drain is situated in a different plane compared to the source and gate. In this configuration, the current flows vertically from the source to the drain.
This design contrasts with the lateral MOSFET, which you can learn more about by referring to examples available HERE https://www.mks.com/n/mosfet-physics.
Vertical MOSFETs are predominantly used in SiC power MOSFETs, as their vertical structure enables the component to exhibit strong voltage withstand capability.
 

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1. What is channel length modulation in SiC Vertical MOSFETs?

Channel length modulation is a phenomenon that occurs in SiC Vertical MOSFETs where the channel length of the device changes with increasing drain voltage. This change in channel length can affect the device's electrical characteristics, such as the threshold voltage and the output resistance.

2. How does channel length modulation affect the performance of SiC Vertical MOSFETs?

Channel length modulation can lead to a decrease in the output resistance and an increase in the drain current, which can result in higher power dissipation and reduced device reliability. It can also cause variations in the threshold voltage, which can affect the switching behavior of the MOSFET.

3. What factors contribute to channel length modulation in SiC Vertical MOSFETs?

The main factors that contribute to channel length modulation in SiC Vertical MOSFETs are the electric field in the channel region and the mobility of the charge carriers. The electric field increases with increasing drain voltage, leading to a decrease in the channel length. The mobility of the charge carriers also decreases with increasing electric field, further contributing to channel length modulation.

4. How can channel length modulation be reduced in SiC Vertical MOSFETs?

To reduce channel length modulation, the device design can be optimized to minimize the electric field in the channel region. This can be achieved by using a thicker gate oxide layer or implementing a lightly doped drain structure. Additionally, the use of advanced fabrication techniques, such as epitaxial growth and ion implantation, can also help reduce channel length modulation.

5. What are the advantages and disadvantages of channel length modulation in SiC Vertical MOSFETs?

The main advantage of channel length modulation in SiC Vertical MOSFETs is that it can improve the device's switching speed and reduce the on-resistance. However, the disadvantages include increased power dissipation, reduced device reliability, and variations in electrical characteristics. Therefore, channel length modulation needs to be carefully considered and controlled during the design and fabrication of SiC Vertical MOSFETs.

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