Mutual alloying of XAs (X = Ga, In, Al) materials: Tuning the optoelectronic and thermodynamic properties for solar energy applications

• Mutual alloying of XAs (X = Ga, In, Al) materials is investigated with DFT.
• XAs materials are suitable for optoelectronic and solar energy applications.
• Energy gap of Ga1−xAlxAs and In1−xAlxAs was found to be increased with x.
• Mutual alloying with different concentrations is useful to tune their properties.

In the present work we did mutual alloying of the versatile XAs (X = Ga, In, Al) materials in order to improve their efficiency and enhance their range of technological applications using state of the art first principles method. We investigate the structural, electronic and thermodynamic properties of Ga1−xAlxAs, Ga1−xInxAs and In1−xAlxAs for x = 0.25, 0.50, and 0.75. Calculations have been performed using the density functional theory (DFT) as implemented within the full potential linearized augmented plane wave plus local orbital (FP-LAPW + lo) method. For exchange and correlation energy treatment, we employed the local density approximations (LDA) as proposed by Wang and Perdew and the generalized gradient approximation (GGA) from Perdew et al. proposed. To calculate the accurate band structure, recently modified Becke Johnson (mBJ) potential was suggested as an alternative. Our calculations show a linear fall in the lattice constant in contrast to linear rise in bulk moduli of Ga1−xAlxAs and In1−xAlxAs with the increase of Al concentration. However the change of indium concentration in Ga1−xInxAs is displaying a reverse effect. The energy band gap of Ga1−xAlxAs and In1−xAlxAs was found to be increased, where a crossover from direct to indirect band gap has been observed with the increase of Al concentration. This direct to indirect crossover was found at 93.4% of Al concentration for Ga1−xAlxAs and at 84.63% of Al concentration for In1−xAlxAs. The effect of the mutual alloying of XAs materials on the thermodynamic properties is comprehensively reported.

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