Light doping effects of rare-earth elements. Sc, Y, La and Lu in rockSalt AlN - first-principles study

Although rare earth (RE) nitride adopt a rock salt as equilibrium structure, the first-principles calculations; based on density functional theory (DFT) with the ultrasoft pseudopotential method and the generalized gradient approximation (GGA), were used to investigate the light doping effects of RE elements : Sc, Y, La and Lu in aluminum nitride ''AlN'' structure, which is well known as hard and wide band gap semiconductor materials. The light introductions of Sc, Y, La and Lu into AlN were obtained using supercell (SC) method. As a results in this paper, ternary alloys which were focused on rock salt RE nitrides revealed that the band gap (Eg) and hardness (Hv) were significantly reduced from 4.523 eV (34.1 GPa), 2.113 eV (28.6 GPa) , 1.285 eV (24.6 GPa), 0.549 eV (22.6 GPa) and 0 eV (15.2 GPa) for AlN, Al${}_{0.75}$Sc${}_{0.25}$N, Al${}_{0.75}$Lu${}_{0.25}$N, Al${}_{0.75}$Y${}_{0.25}$N and Al${}_{0.75}$La${}_{0.25}$N, respectively. All structural, electronic, optic, elastic and thermal parameters were affected by the RE ion contents in the alloys. Some obtained results are consistent well with other available calculations and experimentally measured data.