Structural characterization and Coulomb blockade of a-SiN_x/ nanocrystalline Si /a-SiN_x asymmetric double-barrier structures

Abstract

We have fabricated a series of a-SiN_x/nc-Si/a-SiN_x double-barrier structural samples by plasma-enhanced chemical vapor deposition (PECVD) and subsequent thermal annealing technique. The micro-structural properties of the samples were studied by using Raman scattering spectroscopy, planar and cross-section transmission electron microscopy (TEM). The electrical properties of the samples were investigated by frequency dependence of capacitance voltage (C-V) measurements. Charging effect in the nc-Si was exhibited through the hysteresis phenomena of the C-V curve and explained by F-N tunneling. For the thicker SiN_x barrier layer samples, Coulomb blockade effect was observed in C-V curve for the sample with thinner SiN_xbarrier layer, in which two capacitance peaks appeared, and explained by direct tunneling of electrons into the nc-Si through the tunneling SiN_x layers. From the interval between the two peaks, the Coulomb charging energy of nc-Si dot was estimated.