It's possible to define "logic gate" in terms that just encompass doped silicon, but that's not a particularly useful definition.
This is relevant because there's a claim, implicit in computationalism, that the operation of a logic gate, whatever it's basis of operation, will produce, if properly organised, the phenomenon of consciousness.
Either the concept of a "logic gate" has to be physically defined, or else it has to be accepted that consciousness is not a physical phenomenon.
There's no need for a complete, fundamental understanding. We have sufficient physical definitions of electricity and magnetism that we can form physical theories about them. It doesn't mean that we have total knowledge of what they consist of. However, in order to say that if we rotate conducting wires in a magnetic field we produce electric current, we need all these concepts to be sufficiently precisely defined so that we objectively know what all our terms actually mean. This isn't dependent on what we are using the device for.
When we are talking about logic gates, we need a definition that ensures that we know when something is a logic gate, and when it isn't.
I want a definition that's as solid as that for any physical object or quantity. I want one that's sufficiently objective that the rule can be applied independently of what answer people want to get.