New Nanocrystalline si Floating Gate Structue for Nonvolatile Memory Application

ABSTRACTWe report a direct experiment evidence for holes and electrons charging in a new nanocrystalline Si (nc-Si) floating gate structure (SiO2/nc-Si/SiO2/c-Si) fabricated in-situ by plasma oxidation and layer by layer deposition technique in a plasma enhanced chemical vapor deposition (PECVD) system. In this nc-Si floating gate structures, the thickness of tunneling SiO2 layer is about 2 nm and the mean grain size of nc-Si is 6 nm obtained from Raman scattering and AFM measurements. The discrete quantum level and Coulomb charging energy for a single electron have been observed in large ensemble of nc-Si dots by frequency dependent capacitance spectroscopy, which demonstrates that the Coulomb blockade for electron in nc-Si dots is larger than size fluctuation effects on the quantum confinement for our nc-Si floating gate structure. Quantitatively, the experiment results of capacitance spectroscopy are in good agreement with the theoretical calculations. By contrasted with silicon single electron transistor memory made by using ultra fancy nanotechnology, nc-Si based memory can be fabricated with a minimum perturbation of conventional silicon technology and may be closest to industrial application.