First-principle calculations to investigate structural, electronic, mechanical, optical, and thermodynamic features of promising (La, In)-doped AlSb for optoelectronic applications.

CONTEXT: A remarkable change in lattice parameters and bulk modulus is achieved by the suitable addition of Al (Al1-x Lax Sb) and In (Al1-x Inx Sb) atoms in the AlSb compound. Electronic responses like band structure, the total partial density of states, and the elemental density of states are thoroughly investigated. The computed values indicate that the binary compound AlSb is an indirect band gap and an optically inactive response. After increasing the doping concentrations (0.25, 0.5, 0.75) of La and In in AlSb, the band gap changes from indirect to direct nature. Hence, Al1-0.75 La0.25 Sb, Al1-0.50 La0.50 Sb, Al1-0.75 In0.25Sb, and Al1-0.50 In0.50Sb become optically active. The illustrious roles of Al-3p and In-4d states on the band gap and nonlinear responses of these compounds are extensively explored by the comparison between the computed results of ultra-soft and norm converging pseudopotentials. The excess specific heat (CV), enthalpy of mixing (Hm), and phonon dispersion curves resulting from the concentrations "x" are estimated in order to investigate the thermodynamic stability responses of the pristine and doped AlSb. The obtained CV and thermal coefficient statistics for Al1-x Lax Sb and Al1-x Inx Sb may be useful for a good mapping of experimental results and examining these compounds' enharmonic responses. There is a valuable change in optical characteristics like dielectric functional, absorption, conductivity, and refractive index due to the addition of (La, In) impurities in AlSb. It is further observed that Al1-0.75 La0.25 Sb, Al1-0.50 La0.50 Sb, Al1-0.75 In0.25Sb, and Al1-0.50 In0.50Sb are significantly mechanically stable compared to pristine AlSb. The above results suggest that Al1-x Lax Sb and Al1-x Inx Sb are high-performance optical materials and can be promising potential candidates for optoelectronic applications. METHODS: The structural, electronic, mechanical, vibrational, and optical responses of the pure and doped Al1-0.75 La0.25 Sb, Al1-0.50 La0.50 Sb, Al1-0.75 In0.25Sb, and Al1-0.50 In0.50Sb are investigated, using Heydscuseria-Ernzerhof screened hybrid functional (HSEO6) and generalized gradient approximation (GGA) with norm-converging and ultra-soft pseudopotential techniques in the density functional theory.