Nanoscale physics

Electrical Properties of Silicon Oxide Films with Si and Metal Nanoclusters
Kizjak A.Yu.1, Evtukh A.A.1, Bratus’ O.L.1, Antonin S.1, Ievtukh V.A.1, Fedotov A.K.2
1 V. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine, 41 Nauki ave., 41, Kyiv, 03028, Ukraine. 
E-mail: anatoliy.evtukh@gmail.com
2 Belarusian State University, 4 Nezavisimosti ave , Minsk 220030, Belarussia. E-mail: fedotov@bsu.by.

At the present, much attention is paid to the study of the physical properties of structures with nanoinclusions (nanocomposites), which is due to their potential use, for example, in electronics, optoelectronics, sensors, etc. The presence in such structures under certain conditions of the so-called "negative differential capacity" effect makes it possible to use them for the development of new types of non-turn inductances with controlled parameters that can be used in integrated circuits. Promising for the development of such structures are nanocomposite semiconductor-dielectric materials, which completely fit into the principles of planar silicon technology. The aim of this work is to study the mechanisms of electrical conductivity of semiconductor / SiO2 nanostructures containing Si and metals (Fe, Al) nanoparticles.
The nanocomposite films with silicon and metal inclusions were obtained by ion-plasma co-sputtering of composite target containing silicon, iron or aluminum in an argon and oxygen atmosphere. The silicon oxynitride (SiOxNy) films with aluminum inclusions were also deposited. Following high-temperature annealing at T = 1100ºC of these films allowed to form the silicon nanocrystals and iron or aluminum nanoparticles. The following methods were used to determine the parameters of the films (refraction index, thickness) and analysis of the conductivity mechanisms: IR spectroscopy, spectral ellipsometry, current-voltage (I-V) characteristics at different temperatures from 100 to 340 K and capacity-voltage (C-V) measurements.
Based on the results of the measurements the mechanisms of electrical conductivity of the resulting films were analyzed and the influence of high-temperature annealing on these mechanisms was observed. The presence of metallic inclusions in SiOxNy leads to a significant increase in leakage (current at low voltages). Magnitude of these leakages depends on the annealing medium (Fig. 1). It is also necessary to point out that in the case of the silicon-enriched SiOx film the annealing in argon at T = 1100 °C reduces the electrical conductivity at higher voltages compared to annealing in nitrogen, but in the same films with metallic inclusions the situation is reversed.

Fig. 1. Influence of the annealing medium on the conductivity of the SiOxNy(Al) films: a) annealing in N2; b) annealing in Ar

This work was supported in part by the Ministry of Science and Education of Ukraine under joint Belorussia-Ukraine Project M/160-2017.