In linear scale, we have a quadratic dependence In log-scale, we have an exponential dependenceġ5 ( ) I = I e - e ( ) ( ) d n Dn = dx No recombination Dn = Ax + B l dnĢ n No recombination Dn = Dn = Ax + B dx 2 dn d D n 2 = D + G - R dt n dx 2 l y varies as kVG dn n - n (qDn / l) (e-(Y - Vs)/UT - e-(Y - Vd)/UT) J = qD = qD source drain = n dx n l ( ) ( ) ( ) k V - V / u k V - V / u I = I e - g S T e g d T Use subthreshold operation as the fundamental case Sub-VT operation simplifies this 2D problem to 2 1D problems Allows intuition across sub-VT and above-VT operationġ0 Channel Current Dependence on Gate Voltage (n-well) CMOS Process = nFETs and pFETs are available all p-n junction must be reversed bias We create a silicon-oxide “stencil” (or mask) We get highly repeatable gates because the gate acts as a stencil as well N-type ND P-type NA First-Principles Modelĥ A MOSFET Transistor Source Drain Gate Drain Gate Source SubstrateĦ Self-Aligned Process How do we make a basic transistor element?
The models are then available for association to the relevant power semiconductor component types in PLECS.Ec qDV Ec E0 Ec Ef Case I: P(E) ~ exp( - E0 /kT) Case II: P(E) ~ exp( - ( E0 - qDV)/kT) Ratio of Case II to Case I = 1 P(E) = ~ e-(E-Ef)/kT 1 + e-(E-Ef)/kT exp( DV / UT ) UT = kT/qģ P-N Junctions Depletion Layer or Region N-type ND P-type NA qND Charge xml files to the list of "Thermal description search paths" in the "Thermal" tab of the PLECS Preferences window. In order to use these models, add the folder(s) containing the. The thermal models can be downloaded from the manufacturer's web page.
The following manufacturers provide ready-to-use PLECS models for their power semiconductors.