The organic electroluminescent (EL) diodes have been fabricated with one layer of 8-hydroxyquinoline neodymium (Ndq3) as the EL-emitting layer deposited on cleaned indium/tin oxide (ITO) at different deposition rates. The Ndq3 thin film surfaces were scanned by atomic force microscopy (AFM), it was found that the organic thin film uniformity has strong influence on the Ndq3 EL intensity and break-down voltage of the EL diode.