Structural, Optoelectronic, Mechanical and Thermoelectric Characteristics of Wurtzite In _x Al _1‐x N: A First‐Principles Study

Abstract

ABSTRACT A comprehensive first‐principles investigation of the structural, optoelectronic, mechanical, and thermoelectric properties of wurtzite In x Al 1‐x N (0 ≤ x ≤ 1) alloys was performed using the linearized augmented plane wave (FP—LAPW) method within the Wien2K code. The equilibrium structural parameters including lattice constants a and c and their ratio c/a were calculated employing the Wu—Cohen generalized gradient approximation (WC—GGA), and showing excellent agreement with available experimental data, which confirms the reliability of the computational approach. The electronic behavior of wurtzite In x Al 1‐x N, modeled through the advanced nKTB—mBJ potential, with their calculated band gaps ranging from 5.54 to 0.87 eV confirm their semiconducting nature and tunability across a wide spectral range. Optical analysis reveals that the static dielectric constant (ε 1 (0)) ranges from 3.27 to 5.69, the refractive index varies between 1.89 and 2.38, and strong absorption occurs above energies (8.87–18 eV), indicating potential for UV—visible optoelectronic applications. The studied wurtzite In x Al 1‐x N alloys demonstrate mechanical stability with a brittle character, evidenced by B/G ratios ranging from 1.279 to 1.561 (<1.75), ν values between 0.19 and 0.236 (<0.25), and negative Cauchy pressures. Thermoelectric behavior was studied by applying Boltzmann transport theory as implemented in BoltzTrap, revealing ZT values close to 0.82 at higher temperatures, indicating strong potential for thermoelectric applications. The Slack model was applied to estimate lattice thermal conductivity, providing insights into phonon transport behavior and heat management in device applications.