I can't understand how does the absence of an electron at a point creates a positive charge there. In my opinion, it is wrong on account of conservation of charge. Because if we consider an electron(at a point A) as a system, and if the electron get displaced to another point B(in the system), then if we apply the concept of holes -> firstly, the charge of the system was -e and now the charge is +e-e = 0 !!. Which shows that charge can be destroyed. can any one help???