Use this semiconductor calculation for first-order device, material, fabrication, interconnect, packaging, or reliability estimates when every coefficient and unit convention is known.

Base diffusion coefficient (cm^2/s)

Required number in cm^2/s. Minority-carrier diffusion coefficient in the base.

Base width (um)

Required number in um. Neutral base width.

The cited overview of Semiconductor device supplies background for the terminology and domain context used by this tool.^[1]

Compute the minority-carrier base transit time of a bipolar transistor from base width and diffusion coefficient. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Transit time (ps)

Returned number in ps. Base transit time.

• Material composition, geometry, process history, temperature, electric field, bias, interfaces, parasitics, and fitted parameter ranges can invalidate a compact semiconductor model.
• Base diffusion coefficient must be at least 5e-324.
• Base width must be at least 5e-324.
• Use finite inputs in the displayed units, preserve source measurements and assumptions, and independently verify consequential decisions.

Compare the estimate with measured process data, current device documentation, and a higher-fidelity circuit, field, thermal, quantum, or TCAD model when the decision requires it.

• BJT Base Transport Factor Calculator

  Compute the BJT base transport factor from base width and minority-carrier diffusion length.

• Diffusion Length Calculator

  Compute the diffusion length from a diffusivity and anneal duration. Length = sqrt(diffusivity × time).

• Anneal Activation Fraction Calculator

  Compute the fraction of dopant activated by an anneal from a first-order activation rate and anneal duration. Fraction = 1 - exp(-rate × time).