Charge storage in Si nanocrystals embedded in SiO 2 with enhanced C-AFM

Abstract

A Conductive Atomic Force Microscope (C-AFM) has been used to investigate the nanometer scale electrical properties of Metal-Oxide-Semiconductor (MOS) memory devices with Silicon nanocrystals (Si-nc) embedded in the gate oxide. This study has been possible thanks to the high lateral resolution of the technique, which allows to characterize areas of only few hundreds of nm 2 and, therefore, the area that contains a reduced number of Si-nc. The results have demonstrated the capability of the Si-nc to enhance the gate oxide electrical conduction due to trap assisted tunneling. On the other hand, Si-nc can act as trapping centers. The amount of charge stored in Si-nc has been estimated through the change induced in the barrier height measured from the I-V characteristics. The results show that only ~20% of the Si-nc are charged. These nanometer scale results are consistent with those obtained during the macroscopic characterization of the same structures. Therefore, C-AFM has been shown to be a very suitable tool to perform a detailed investigation of the performance of memory devices based on MOS structures with Si-nc at such reduced scale.

Nanoscale electrical characterization of Si-nc based memory metal-oxide-semiconductor devices

“…Note, however, that when identical devices with a polysilicon gate are characterized at a macroscopic scale ͑inset of Fig. 22 Although the origin of these traps is not clear ͑further studies, which are out of the scope of this work, should be performed to clarify this point͒, they could be related to native or sample deprocessing defects. 4, circles͒, the value found for the potential barrier is 3.08 eV, closer to the 3.2 eV expected.…”

Charge transport along luminescent oxide layers containing Si and SiC nanoparticles

“…Now if we polarize the device negatively, the same behaviour is observed, that is, from 0 to À30 V, the curve corresponds to (3), and the reverse sweep from À30 to 0 V labelled (4) is more resistive. Likewise as in positive polarization, the same measurement will exhibit curve (4). Then, if a positive polarization is applied, curve (1) is found again, followed by curve (2).…”

“…A large amount of potential applications have been demonstrated such as LEDs [1,2], memories [3,4] or switch components exploiting nonlinearity properties of Si-nc [5]. The opening of the gap of silicon due to quantum confinement has allowed to observe photoluminescence (PL) in the red-infrared spectral region [6].…”

Improving the Consistency of Nanoscale Etching for Atomic Force Microscopy Tomography Applications

“…Thus, with the advancement of micro-and nanoscale technologies, AFM has offered significant insight in materials research (Gerber and Lang, 2006;Hui and Lanza, 2019). For example, conducive AFM has been of particular importance in such fields as resistance switching memories (Brivio et al, 2014;Lanza, 2014;Bousoulas et al, 2015; and energy harvesting, storage and generation systems (Lanza et al, 2014;Tennyson et al, 2017), and the investigation of broader functional material properties such as charge trapping (Porti et al, 2005;Polspoel and Vandervorst, 2007), leakage (Lanza et al, 2012;Pirrotta et al, 2013), breakdown (O'Shea et al, 1995), and reliability (Porti et al, 2007).…”