Answer
No free electron is generated by the electron excitation involving an acceptor impurity atom because the electron is excited from the valence band into the impurity level within the band gap; thus, no free electron is introduced into the conduction band.
Work Step by Step
No free electron is generated by the electron excitation involving an acceptor impurity atom because the electron is excited from the valence band into the impurity level within the band gap; thus, no free electron is introduced into the conduction band.