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

Forward current (mA)

Required number in mA. Forward bias current. Must be at least 0 mA; 0 yields 0 nF.

Lifetime (ns)

Required number in ns. Minority-carrier lifetime. Must be greater than 0 ns.

Ideality factor

Optional number. Diode ideality factor. Must be at least 1.

Temperature (K)

Optional number in K. Device temperature. Must be greater than 0 K.

The cited overview of P–n junction supplies background for the terminology and domain context used by this tool.^[1]

Compute the diffusion capacitance of a forward-biased diode from stored-charge lifetime and current. Formula: Cdiff [nF] = 1e9 · (τ [ns]·1e-9 · I [mA]·1e-3) / (n · Vt [V]), where Vt = k·T/q (k=1.380649e-23 J/K, q=1.602176634e-19 C). Equivalent: Cdiff [F] = τ·I/(n·Vt). Inputs: I ≥ 0 mA, τ > 0 ns, n ≥ 1 (default 1), T > 0 K (default 300 K). Output: Cdiff ≥ 0 nF. Assumes low-level injection, negligible depletion capacitance, and quasi-neutral stored charge τ·I. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Capacitance (nF)

Returned number in nF. Diffusion capacitance. At least 0 nF.

• Material composition, geometry, process history, temperature, electric field, bias, interfaces, parasitics, and fitted parameter ranges can invalidate a compact semiconductor model.
• Forward current must be at least 0.
• Lifetime must be at least 5e-324.
• Ideality factor must be at least 1.
• Temperature 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.

• Diode Ideality Factor Calculator

  Extract the diode ideality factor n from two forward-bias points on the exponential Shockley relation. Formula: n = (V2 - V1) / (Vt·ln(I2/I1)), where thermal voltage Vt = k·T/q (k=1.380649e-23 J/K, q=1.602176634e-19 C). Inputs: I1>0 mA, I2>0 mA and I1≠I2, V1 and V2 finite V, T>0 K (default 300 K). Output: n>0 (physical diode typically 1 ≤ n ≤ 2; n=1 ideal diffusion, n≈2 recombination/generation; n outside 1-2 indicates series resistance, high injection, or measurement error). Assumes forward exponential region, negligible series resistance, and constant temperature.

• Semiconductor Effective Density Conduction Band Calculator

  Compute the conduction-band effective density of states from a density-of-states effective mass and temperature. Formula: Nc(T) = 2.51e19·(m*_dos/m0)^{3/2}·(T/300)^{3/2} [cm⁻³], where 2.51e19 cm⁻³ is the 300 K value for m*=m0, m*_dos>0 is the DOS effective mass ratio, T>0 K is lattice temperature (default 300 K). Inputs: m*_dos>0 (default 1), T>0 K (default 300 K). Output: Nc>0 cm⁻³. Assumes parabolic band, Boltzmann statistics, and isotropic effective mass.

• DRAM Retention Time Calculator

  Estimate DRAM retention time from cell capacitance, allowable refresh voltage drop, and leakage current. Formula: t_ret [s] = (C [fF]·1e-15·ΔV [V])/(I_leak [fA]·1e-15) = C·ΔV/I_leak, derived from charge Q=C·ΔV leaking at rate I_leak. Inputs: C>0 fF, ΔV>0 V, I_leak>0 fA. Output: t_ret>0 s. Assumes constant leakage, no refresh overhead, and that the cell holds charge C·V until droop ΔV.