The a-SiNx/nc-Si/a-SiNx sandwiched structures are fabricated in a plasma enhanced chemical vapour deposition (PECVD) system on n-type Si substrate. The nc-Si layer in thickness of 5 nm is fabricated from hydrogen diluted silane gas by layer-by-layer deposition technique. The thicknesses of tunnel and control SiNx layer are 3 nm and 20 nm, respectively. Conductance-voltage and capacitance-voltage measurements are used to study the charges tunnelling and storage in the sandsiched structures. Distinct frequency-dependent conductance peaks due to charges tunneling into the nc-Si dots and capacitance-voltage hysteresis characteristic due to charges storage in the nc-Si dots are observed in the same sample. The experimental results demonstrate that by controlling the thickness of tunnel and control SiNx layers charges can be loaded onto nc-Si dots via tunnelling and be stored in a-SiNx/nc-Si/a-SiNx structures.