The current blocking and charge accumulation effects of an ITO/Si-rich SiOx/p-Si MOS diode with buried Si nano-dots and SiOx/Si interfacial Si nano-pyramids are characterized. The ITO/Si-rich SiOx/p-Si MOS diodes exhibits the 3.5 Â± 0.2 nm large Si nano-dots with volume density of 4-5Ã1018 cm-3. At the SiOx/p-Si interface, the area density of Si nano-pyramids is increasing from 1.3Ã109 to 1.6Ã1011 cm-2, which greatly decreases turn-on voltage of the MOS diode from 182 to 52 V, thus enhancing the electro-luminescent power from 17.5 to 50.4 nW. The current blocking phenomenon of such a MOS diode become serious with lengthening step-voltage delay, indicating that a significant charge accumulation associated with a strong screening field is generated within Si-rich SiOx layer. It was observed that the turn-on voltage with Si nano-pyramids evidently decreases to 31.6 V under reverse biased conditions for tunneling holes. Counter-clockwise C-V hysteresis analysis reveals a flat-band voltage shift of 8.5 V for electron and -12.9 V for hole, showing nonlinear function with either Si nano-dot volume or density. The C-t retention shows higher charge loss rate for electrons (7.6%) than for holes (1.5%) within 0.5 hr due to low SiOx/Si nano-dot barrier.