Gate oxide
Beginner
A layer of glass, far thinner than a soap bubble, between a transistor’s gate and the silicon. It stops electricity from flowing into the gate.
Novice
The insulating film, originally silicon dioxide, between the gate and the channel. Thinner oxide gives the gate a stronger grip on the channel but lets more current tunnel through.
Expert
About 4.1 nm (electrical) for SKY130’s 1.8 V NMOS. At around 1 nm, leaks too much by tunneling, so advanced processes use high-k dielectrics that give the same capacitance with a physically thicker film.