Most undergrad textbooks on microelectronics (those covering semiconductors, diodes, BJT's, FET's, etc.) that I have laid my hands on discuss semiconductor concepts such as charge carries, drift, recombination, among others, to explain why transistors behave the way they do, and then present mathematical models for how different types of transistors work (e.g. IV curves) in order to analyse circuits involving them.
My question is, can state-of-the-art transistors such as those in modern CPU's be modeled by similar formulas? Given that modern transistors based on 7 nm technology can be only a few atoms in size (~30), do the same concepts apply, or do you really need PhD-level knowledge to even begin to understand how they actually work?
I've seen from other sources how ASIC foundries will share pspice models of the transistors that they can handle to customers and that they tend to be extremely complicated with dozens if not hundreds of parameters, so I got curious about this.