Abstract
Optical thin films of nanoscale particles have recently received much attention since its special optical characteristics can dramatically increase sensitivity of surface plasmon-based sensors. In order to well control assembly process, understanding optical properties of nanoparticles films and accurately predicting the behaviors of optical devices, correct optical constants are necessaries. We added gold nanoparticles before and after measuring the spectroscopic ellipsometric parameters (TanΨ, CosΔ) to calculate the optical constants, thickness and porosity, and measured the film thickness by grazing incidence x-ray reflectivity (XRR) and cross-section SEM. Finally we use the optical constants of gold nanoparticles to simulate and get the optimized thickness of gold film for SPR measurement. We report the fabrication of germanium quantum dots and porous Ge film on silicon oxide and their growth mechanism. We deposited germanium quantum dots by inductively coupled plasma chemical vapor deposition at 400 °C. Gold nanoparticles, attached to silicon oxide through a self–assembled monolayer, were adopted as catalysts to allow access to a vapor–liquid–solid process. The density of polycrystalline germanium dots is 1.46 x 1011/cm2, which is consistent with the density of the gold nanoparticles. The mechanism by which the undesirable gold catalysts are removed during the germanium dot and porous Ge film growth process have been elucidated. This technique provides a low-temperature process for the fabrication of devices consisting of germanium quantum dots on an insulator surface.