FIRST-PRINCIPLES CALCULATIONS FOR THE STRUCTURAL AND ELECTRONIC PROPERTIES OFScxAl1-xNALLOYS

The first-principles calculations based on Density Functional Theory (DFT) within generalized gradient approximation (GGA) of Engel–Vosko–Perdew–Wang and modified exact exchange potential of Becke–Johnson have been introduced for the structural and electronic properties of theScxAl1-xNalloys, respectively. The present lattice constants calculated for theScAlNalloys and the end compounds (AlNandScN) are found to be in very good agreement with the available experimental and theoretical ones. The stable ground state structures of theScxAl1-xNalloys are determined to be wurtzite for theScconcentration less than ~0.403 and rock-salt for the higherScconcentrations. The present electronic band structure calculations within Becke–Johnson scheme are found to be capable of providing energy band gaps of theAlNandScNcompounds very close to the ones of the available experiments and expensive calculations. According to the calculations of Becke–Johnson potential, theScxAl1-xNalloys in the wurtzite and zinc-blende structures are direct band gap materials for theScconcentrations in the ranges of(0.056 ≤ x ≤ 0.833)and (0.03125 ≤ x ≤ 0.0625,0.375 ≤ x ≤ 0.96875), respectively. However, theScAlNalloys in the rock-salt phase are determined to be direct band gap materials for total range of theScconcentration considered in this work. While the energy gaps of the RS-AlScNalloys are found to be extending from near ultraviolet to near infrared with a large (negative) bowing, the ones of the WZ-AlScNand ZB-AlScNalloys are determined to be varying in a small energy range around near ultraviolet with a small (negative) bowing.