We report a Coulomb blockade induced negative differential resistance (NDR) effect at room temperature in a self-assembly Si quantum dots (Si-QDs) array (Al/SiO2/Si-QDs/SiO2/p-Si), which is fabricated in a plasma enhanced chemical vapor deposition system by using layer-by-layer deposition and in-situ plasma oxidation techniques. Obvious NDR effects are directly observed in the current-voltage characteristics, while corresponding capacitance peaks are also identified at the same voltage positions in the capacitance-voltage characteristics. The NDR effect in dot array, arising from the Coulomb blockade effect in the nanometer-sized Si-QDs, exhibits distinctive scan-rate and scan-direction dependences and differs remarkably from that in the quantum well structure in the formation mechanism. Better understanding of the observed NDR effect in SiQDs array is obtained in a master-equation-based numerical model, where both the scan-rate and scan-direction dependences are well explained. (C) 2007 Elsevier B.V. All rights reserved.