Influence of Gold on Structural Defects of Silicon

Abstract

In this research, a comprehensive study of the effect of doping silicon with gold on the optical properties and morphology of silicon layers was carried out. For this purpose, the methods of Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were used. The results of the study showed that the transition from original silicon to gold-doped silicon leads to significant changes in the optical properties and morphology of the layers. Raman spectra showed characteristic peaks in the regions of 144, 304, 402, 464, 522, 948 and 973 cm–1, associated with the violation of long-range order of the crystal lattice and the interaction of gold with silicon. The intensity and position of the peaks in the spectra allowed us to draw conclusions about structural changes, including a decrease in crystallinity and the formation of amorphous and nanocrystalline structures in the samples after treatment at 1373 K. New peaks in the Raman spectra associated with Au-Au stretching and the formation of new bonds Si-Au, confirm the processes in silicon layers when alloyed with gold. SEM studies provided information on the structure, chemical composition and arrangement of n-Si-Au and p-Si-Au samples. The spherical arrangement of gold atoms on the surface of single-crystalline silicon was experimentally established, which indicates the diffusion of gold and the formation of gold silicate, which introduces a positive charge to the interface. Morphological changes included an increase in the number of agglomerates with nanocrystals smaller than 7–9 nm and an increase in the transparency of the layer. These results indicate the possibility of improving the photosensitivity of heterostructures with a Si–Au composite layer due to the quantum-size and plasmonic effects of inclusions containing silicon and gold nanoparticles.