Okay so we have a pMOS transistor with n-type materials on the sides, and a p-type material in the middle. We charge the metal positively so that electrons are attracted towards it, and that creates a channel for electrons to pass. That’s all well and good.
However, why can’t we charge the same pMOS transistor’s gate negatively? If we do so, the electrons should be repelled to the bottom of the transistor (rather than the top) and it should still create a channel for electrons to pass through, right? What’s the catch?