The design of a 600 V-Class Superjunction VDMOS (SJ-VDMOS) with fast recovery diode by electron irradiation is presented in this paper. Experimental measurements and numerical simulations are conducted in order to analyze the effect of the charge imbalance of the pillars and the fluence of electron irradiation on: the characteristics of the diode, the breakdown voltage, and the avalanche capability of the device. The experiments show that the breakdown voltage of the devices is influenced by the electron irradiation and the charge imbalance (C.I.) between the n- and p-pillars. The research results indicate that the breakdown voltage of the devices with higher doped p-pillars (Qp > Qn) increased due to the compensation of boron in the p-pillar after the electron irradiation process. Additionally, the single pulse avalanche energy capability of the devices is also investigated by simulations and experiments, and the results show that the avalanche characteristics of the devices with Qp > Qn are superior to the case of Qp = Qn and Qp < Qn after irradiation. Finally, the reverse recover charge (Q(rr)) of the devices has reduced by 62% after electron irradiation experiments without decreasing its breakdown voltage. (C) 2012 Elsevier Ltd. All rights reserved.