Si Bandgap in Device Modeling (Silvaco Atlas)

In summary, there is a discrepancy in the default bandgap value for silicon in Silvaco Atlas compared to other modern references. The Atlas manual explains that although this value may not be accurate, it is used because other material parameters and models are tuned using these band parameters. The reason for the difference in bandgap values is due to the effects of doping.
  • #1
cmos
367
1
I recently noticed that in Silvaco Atlas (device modeling software), the default bandgap of silicon is given as 1.08 eV. This is at 300 K, no bandgap narrowing, and no other secondary effects - it is default. However, most (all?) of the modern references (e.g. Sze, Streetman, Pierret) give the silicon bandgap to be 1.12 eV.

Going back to the Atlas manual, it says the following, "... although these band parameters may be physically inaccurate compared to bulk silicon measurements, most other material parameters and models are empirically tuned using these band parameters."

I'm just wondering if anybody has any insight on the history of why 1.08 eV appears here or if anybody knows of other software models where this number appears.
 
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  • #2
The biggest reason: doping. The dopant energy levels are inside the intrinsic band-gap and thus the effective doped band-gap is smaller than the bulk intrinsic (undoped) band-gap. E.g. Boron doping shifts by 0.045 eV which is about the same difference.
 

What is the significance of the Si bandgap in device modeling?

The Si bandgap is a crucial parameter in device modeling as it determines the energy required to promote electrons from the valence band to the conduction band. This directly affects the electrical properties of a device, such as its conductivity and resistivity.

How is the Si bandgap determined in device modeling?

The Si bandgap is typically determined experimentally through measurements of the energy gap between the valence and conduction bands. This data is then used in device modeling software, such as Silvaco Atlas, to accurately simulate the behavior of devices.

Can the Si bandgap be modified in device modeling?

Yes, the Si bandgap can be modified in device modeling software, such as Silvaco Atlas, to simulate different material properties or doping levels. This allows for the exploration of various device designs and optimizations.

How does the Si bandgap affect the performance of semiconductor devices?

The Si bandgap plays a critical role in determining the electrical properties of semiconductor devices. A smaller bandgap results in a higher concentration of free electrons, leading to higher conductivity and faster device operation. On the other hand, a larger bandgap results in lower conductivity and slower device operation.

What are the limitations of using the Si bandgap in device modeling?

While the Si bandgap is a crucial parameter in device modeling, it is important to note that it does not fully capture the complex behavior of real-world devices. Other factors, such as impurities and defects, can also significantly influence device performance and must be considered in conjunction with the Si bandgap in device modeling.

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