ZnO films with orientations of (001), (110), and (100) were fabricated on silicon by different substrate biases at low temperature. Dynamic cathodoluminescence (CL) dependence on electron bombardment revealed unstable Zn-N bonding if N2 was used as a predecessor. CL under various accelerated voltages showed the possible energies of Zn-N. N-related photoluminescence (PL) at low temperature confirmed that nitrogen was released after annealing. These N-doping behaviors agreed to the theoretical calculation.