Final answer:
An n-type semiconductor remains electrically neutral because each added negative charge carrier (electron) from the donor atoms is balanced by a corresponding positive charge in the created ions; thus, the overall charge remains balanced.
Step-by-step explanation:
An n-type semiconductor is electrically neutral despite having an excess of negative charge carriers because the overall charge remains balanced. In the process of doping, where a semiconductor is added with donor atoms that have more valence electrons than the semiconductor's base material, these extra electrons become conduction electrons. However, each donor atom becomes positively charged (a positive ion) after donating its extra electron.
This means that for every additional negative charge carrier (electron) introduced into the semiconductor, there's a corresponding positive charge remaining in the donor ion. The total number of negative charges supplied by the free electrons is equal to the total number of positive charges in the form of immobile ions. Hence, electrical neutrality is maintained. The flow of these negative charge carriers (electrons) is what gives the n-type semiconductor its conductivity.