We studied the Nb doping effect on the electrical characteristics of MOCVD-PZT capacitors using uniformly Nb-doped Pb(Zr, Ti)O3 (UND-PZT) and δ-Nb-doped PZT (DND-PZT) prepared by MOCVD. The 2Pr for UND-PZT was small and the UND-PZT hysteresis shifted in a positive direction. However, the 2Pr for DND-PZT decreased by only 5.5% and the hysteresis of DND-PZT didn't shift. In addition, the leakage current of DND-PZT decreased by one order at low bias compared to non-doped PZT, because the δ-Nb-doping layer maintains the barrier height, higher than that of none-doped PZT due to defect compensation. As a result, Nb1% DND-PZT was well suited to use Nb doping which decreases leakage current at low voltage and maintains 2Pr.