Computer study of the Raman spectra and infrared optical properties of gallium nitride and gallium arsenic nanoparticles with SiO₂ core and shell

Abstract

The J(ω) Raman spectra of the $( {\text{GaN)}}_{ 1 2 9}$, $( {\text{SiO}}_{ 2} )_{86}$, and $( {\text{GaN)}}_{ 5 4}$ $( {\text{SiO}}_{ 2} )_{50}$ nanoparticles as well as the optical properties of silicon dioxide and gallium arsenide nanoparticles and the four-component particles based on them were calculated using the molecular dynamics method. The spectrum of $( {\text{SiO}}_{ 2} )_{86}$ had three broad bands only, whereas the Raman spectrum of $( {\text{GaN)}}_{ 1 2 9}$ contained a large number of overlapping bands. The shape of Raman spectra for four-component particles depends strongly on the way the ${\text{GaN}}$-, ${\text{GaAs}}$-, and ${\text{SiO}}_{ 2}$-components are located in the nanoparticle. Increasing the temperature (from 300 K upto 1500 K) of nanoparticles causes a significant rise in the intensity of the Raman spectrum. Thus, the odd J(ω)-spectrum peaks for the nanoparticle with the ${\text{SiO}}_{ 2}$-core shift in opposite directions, but this heating does not lead to the shift of J(ω)-spectrum peaks for the $( {\text{GaAs)}}_{ 5 4}$ $( {\text{SiO}}_{ 2} )_{50}$ nanoparticle with ${\text{SiO}}_{ 2}$-coating. The refractive index and absorption coefficient as well as the number of optically active electrons depend weakly on the arrangement of the conductor (${\text{GaAs}}$) and isolator (${\text{SiO}}_{ 2}$) in the nanoparticle.