The growth mechanism in self-assembly nanostructures of silicon/silicon dioxide interface

Abstract

Silicon nanodots is a common zero-dimensional nanomaterial investigated for single-electron device applications in integrated circuits. The current study attempts to look into the ever-popular silicon self-assembly nanodot grown on different substrates, with emphasis on its growth theory and characterizations. Discrepancy in its growth theories has led to misunderstanding and therefore innovative approaches are presented in this study to clarify and resolve the existing problems. A radio-frequency magnetron sputtering method was used for Silicon nanodots deposition, with the following conditions: argon gas flow rate 5-10 sccm, substrate temperature between 300-600 ºC, deposition time 7-20 minutes, and radio-frequency power between 100-150 W. This research covers both experimental and simulation works including the classical theory of nucleation. Generally, important parameters were first calculated then simulated using computer programming, and finally matched in order to estimate the values of critical energy ?G*, critical radius r*, surface energy ?, and free energy change per unit area ?Gv. The associated Volmer-Weber growth mode was then predicted. Observably, optimum growth parameters for the inception of silicon nanodots were found to be at 600 ºC/10 minutes/100W formed on corning glass substrate. Structural and optical properties have been characterized using atomic force microscope AFM, energy-dispersive X-ray spectroscopy EDX, X-Ray diffraction XRD, photoluminescence PL and scanning electron microscopy SEM. In addition, the AFM characterization results show the existence of nanodots with the estimated average size of 34.4 nm. The results from PL spectrum reveal the presence of a peak which corresponds to a bandgap energy of 1.80 eV and this was attributed to the quantum confinement of electron–hole pairs in quantum wells. A further confirmation using EDX measurement was made which showed the existence of 0.48 at.% of silicon on the substrate. XRD analysis reveals the crystalline structure for high temperature conditions due to orderly silicon nanodots formed on the substrate. The results proved that the properties of silicon nanodots on quartz SiO2, corning glass (7059) and silicon substrates were strongly dependent on the experimental conditions.