Flash memory structure in which a silicon quantum dot embedded in the gate dielectric region between the channel and the control gate is considered. A self-consistent simulation for such memory devices is performed and aims to understand the relationship between the device structure and the meaningful quantities, as required for an efficient device operation. In this study, both the traditional SiO2 and HfO2 high-k dielectrics are being explored, and their results are compared and contrasted. In particular, the superiority of HfO2 over the SiO2 is demonstrated through various interlocking investigations on the relationships between the tunneling current, dielectric thickness, barrier height, programming and retention times.