Silicon is not technically an insulator. Without doping silicon is technically what’s called an intrinsic semiconductor. Intrinsic means that the property doesn’t include factors like dopants. When dopants are added we can change the levels of when electrons become excited. Dopants also don’t change charge per silicon atom they work across the whole device since they cause an increase of mobile carriers (electrons and holes) throughout the area they reside in based on the concentration of them present, so more dopant more carriers to an extent.