Different charging behaviors between electrons and holes in Si nanocrystals embedded in SiNx matrix by the influence of near-interface oxide traps**Project supported by the National Basic Research Program of China (Grant No. 2010CB934402) and the National Natural Science Foundation of China (Grant No. 11374153).

Abstract

Si-rich silicon nitride films are prepared by plasma-enhanced chemical vapor deposition method, followed by thermal annealing to form the Si nanocrystals (Si-NCs) embedded in SiNx floating gate MOS structures. The capacitance–voltage (C–V), current–voltage (I–V), and admittance–voltage (G–V) measurements are used to investigate the charging characteristics. It is found that the maximum flat band voltage shift (ΔVFB) due to full charged holes (∼ 6.2 V) is much larger than that due to full charged electrons (∼ 1 V). The charging displacement current peaks of electrons and holes can be also observed by the I–V measurements, respectively. From the G–V measurements we find that the hole injection is influenced by the oxide hole traps which are located near the SiO2/Si-substrate interface. Combining the results of C–V and G–V measurements, we find that the hole charging of the Si-NCs occurs via a two-step tunneling mechanism. The evolution of G–V peak originated from oxide traps exhibits the process of hole injection into these defects and transferring to the Si-NCs.