Investigation of the phase formation from nickel-modified nanostructured silicon

Introduction The nickel-modified nanostructured silicon allows to implement a number of different applications. It is known as promising material for use in devices of silicon microelectronics, for gas sensing and for active... [ view full abstract ]

Introduction

The nickel-modified nanostructured silicon allows to implement a number of different applications. It is known as promising material for use in devices of silicon microelectronics, for gas sensing and for active layers of betavoltaic batteries. Moreover, the nanostructured nickel silicides, which can be obtained during the solid-phase interaction between the Si and Ni, come into use in recent years. Nevertheless, it should be taken into account that the solid-phase reactions in nanocomposites can occur at the interfaces at relatively low temperatures non-typical for similar processes in macrosystems. In this regard, the problem of estimating and predicting the thermal properties of such materials is of primer importance. The present work focuses on the influence of the interphase boundary "nanostructured Si – Ni" on phase formation during heating.

Methods

In this paper, Si/Ni nanocomposite samples were formed by electrochemical etching of p-type silicon and subsequent cathodic electrodeposition of nickel. The obtained samples were characterized by means of scanning electron microscopy and phase X-ray diffraction analysis before and after heat treatment. The thermal behavior of Si/Ni nanocomposites was investigated by means of differential scanning calorimetry (DSC).

Results and Discussion

The results of the X-ray phase analysis reflect the differences in phase composition of Si/Ni nanocomposites from the reference Si/Ni sample based on monocrystalline Si. The diffraction pattern of the sample before the heat treatment shows the signals from the nickel nanosized crystallites. The silicide phases are missing. After heat treatment in argon atmosphere for 20 minutes at 500 °C, the nickel crystallites have aggregated, and the NiSi crystalline phase has formed. In order to investigate solid phase interactions by DSC there were obtained Si/Ni nanocomposite samples on the basis of Si membrane. DSC data showing almost equal behaviour of the nanostructured Si/Ni samples during heating at the temperature range from 25 to 500 °C. To accurately define the temperature characteristics the DSC curves were computer processed with modelling thermal effects using a normal distribution.

The reported study was funded by RFBR according to the research project No. 16-33-00712 мол_a.