The effects of oxidation conditions on structural and electrical properties of silicon nanoparticles obtained by ultra-low-energy ion implantation

摘要

In this paper, we have studied the effect of annealing under slightly oxidizing ambient (N_2 + O_2) on the structural and electrical characteristics of a limited number of silicon nanoparticles embedded in an ultra-thin SiO_2 layer. These nanoparticles were synthesized by ultra-low-energy (1 keV) ion implantation and annealing. Specific experimental methods have been used to characterize the ncs populations. They include transmission electron microscopy (TEM) Fresnel imaging for evaluating the distances and widths of interest and spatially resolved electron energy loss spectroscopy (EELS) using the spectrum-imaging mode of a scanning transmission electron microscope (STEM) to measure the size distribution and density of the ncs population. To perform electrical measurements of these particles, a nanoscale contact (100 nm X 100 nm) was patterned over the samples by electron-beam nanolithography. Room-temperature I-V characteristics of these nano-MGS structures exhibit discrete current peaks which have been associated with single-electron charging of the nanoparticles and electrostatic interaction of the trapped charges with the tunnelling current. The effect of the progressive oxidation of the Si nanoparticles on these I (V) characteristics has been studied and related to the nanocrystal characteristics.