Si Bandgap in Device Modeling (Silvaco Atlas)

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SUMMARY

In Silvaco Atlas, the default bandgap of silicon is set at 1.08 eV at 300 K, contrasting with the widely accepted value of 1.12 eV found in contemporary references such as Sze, Streetman, and Pierret. The Atlas manual acknowledges that while these band parameters may not accurately reflect bulk silicon measurements, they are used to empirically tune other material parameters and models. The discrepancy is particularly relevant in the context of doping, where the effective doped band-gap is reduced due to the positioning of dopant energy levels within the intrinsic band-gap.

PREREQUISITES
  • Understanding of semiconductor physics
  • Familiarity with Silvaco Atlas software
  • Knowledge of bandgap energy concepts
  • Experience with doping effects in semiconductors
NEXT STEPS
  • Research the implications of bandgap narrowing in semiconductor devices
  • Explore the effects of different dopants on silicon bandgap
  • Learn about empirical tuning methods in device modeling
  • Investigate alternative device modeling software and their bandgap parameters
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Device modelers, semiconductor physicists, and engineers involved in semiconductor design and analysis will benefit from this discussion.

cmos
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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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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.
 

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