Thin film transistors were fabricated using ZnO and ZnON semiconductors grown by DC reactive sputtering. After low vacuum annealing at 250 degrees C, ZnON devices exhibit superior electrical performance (mu(sat)=56.3 cm(2)/Vs, Vth = -1.59 V, and SS =0.51 V/dec) in comparison with ZnO devices (mu(sat)= 0.99 cm2/Vs, Vth=3.28 V, and SS =1.22 V/dec). The physical and electronic structures in both materials were analyzed by X-ray diffraction and X-ray absorption spectroscopy, respectively. The chemical bonding states were also examined by X-ray photoelectron spectroscopy. Consequently, nitrogen incorporation in DC reactive sputtering is found to suppress crystallization and enhance electron transport by the formation of Zn-N bonds.