Silicon oxides and silicon nitrides: Structure, properties and applications in memristors

The capacity of memory matrices grows exponentially, but in many approaches the degree of integration of memory elements already reaches physical limits, which stimulates research into the development of new physical principles and new materials for memory elements. Memristors are very promising elements of memory. The memristors are the basis for high-speed, non-volatile, radiation-resistant flash memory matrices of the new generation. The SiO _x (0.3<x≤2) films of various stoichiometry were prepared using two methods: 1) evaporation of Si, SiO and SiO ₂ targets and deposition in high vacuum; 2) plasma enhanced chemical vapor deposition (PECVD). The SiN _x (0.5<x≤4/3) films were deposited using PECVD. Raman scattering spectroscopy, visible and infrared (IR) absorbance spectroscopy and spectral ellipsometry and electro-physical methods were used for studies of the films. According to Raman spectroscopy data, the as-deposited SiN _x (x<1.1) contain amorphous Si clusters, high temperature annealings lead to crystallization of the clusters and forming of Si nanocrystals in such films. As for SiOx films, amorphous Si clusters were observed in asdeposited films with x≤1. These data were confirmed from analysis of ellipsometry data. The current-voltage (I-V) characteristics of the films were studied. Effects of switching from high resistance state (HRS) to low resistance state (LRS) were observed for SiO _x based films. These switching can be used in memristors.