I think you’re missing what at my university is the course: Solid State Physics, followed by a manufacturing course that may contain a lab.

This covers the physics of transistors and the basics from crystals, how to modify the properties of a crystal, and quantum effects. Then you will know how electricity affects a transistor (through field effect).

Basically if you have two wires that are open, then run a live wire near these two wires, the two wires will close. That’s a very high level overview of a field effect transistor.