Charging characteristics of Si nanocrystals embedded within SiO2 in the presence of near-interface oxide traps

In this work we report on the influence of oxide traps-located near the Si substratetunnel oxide interface - on the charging characteristics of Si-nanocrystals embedded within SiO2 layers, by monitoring the admittance characteristics at room temperature. We study this effect in the case of Si-nanocrystals fabricated by LPCVD deposition of α-Si and high temperature thermal oxidation. In the samples investigated in this work, oxide hole traps located almost at the Si-SiO2 interface of the silicon substrate were found to control hole injection and transfer to the Si nanocrystals. Upon capturing a hole the defect energy levels undergo a transition due to lattice relaxation effects and hole charging of the Si-nanocrystals occurs via an inelastic two-step tunneling mechanism. High temperature annealing was found to reduce the density of these near-interfacial defects, therefore reducing the coupling between the Si-nanocrystals and the substrate