Shifting the plasmonic resonance to infrared region for AlP by inducing high S concentration: Indirect to direct band gap

In this work, structural, electronic, dielectric and thermoelectric properties of AlP with the presence of sulfur (S) impurities with various concentrations to form Al1P1_xSx with x = 0.083, 0.166 and 0.25 is studied using the first-principles density functional theory (DFT) based on the generalized gradient approximation (GGA). It was found that the presence of S leads to reducing the lattice parameter due to the strong electronegativity of S, and also leads to a direct band gap and increases the optical band gap, the conduction type of the doped systems are N-type degenerated semiconductor. Also, it is found that the increase of the doping concentration leads to an increase the electrical conductivity and thermal conductivity while it reduces the seebeck coefficient. Moreover, according to the linearity of the behavior obtained, it is found that when AlP is doped with 9.49% of S, the material can be in resonance with the electromagnetic wavelength of 10 mu m that is necessary to detect sun radiations. This study shows that S doped AlP is an appropriate material for Thermoelectric Coupled NanoAntenna (TECNA's) applications.