First principles total energy calculations of the structural and electronic properties of Sc_xGa_1–xN

Abstract

Using first principles total energy calculations within the the full-potential linearized augmented plane wave (FP-LAPW) method, we have investigated the structural and electronic properties of Sc x Ga 1Àx N, with Sc concentrations varying from 0% up to 100%. In particular we have studied the relative stability of several configurations of Sc x Ga 1Àx N in wurtzite-like structures (the ground state configuration of GaN), or in rocksalt-like structures (the ground state configuration of ScN). It is found that for Sc concentrations less than %65%, the favored structure is a wurtzite-like one, while for Sc concentrations greater than %65%, the favored structure is a NaCl-like structure. It is also found that for the wurtzitelike crystals, the fundamental gap is large and direct. For the rocksalt crystals the fundamental gap is small and indirect, but with an additional larger direct gap. In agreement with the experiments of Little and Kordesch [Appl. Phys. Lett. 78, 2891 (2001)] we found a decrease of the band gap with the increase of the Sc concentration.

Wurtzite structure Sc1−xAlxN solid solution films grown by reactive magnetron sputter epitaxy: Structural characterization and first-principles calculations

“…2 The band gap is observed to increase linearly from 2.0 to 3.5 eV with decreasing ScN content from 100% to 0%, respectively, independent of crystal structure. 2,3 ScN is a semiconducting group IIIB nitride with an indirect band gap of 0.9-1.6 eV.…”

“…2 The band gap is observed to increase linearly from 2.0 to 3.5 eV with decreasing ScN content from 100% to 0%, respectively, independent of crystal structure. 2,3 ScN is a semiconducting group IIIB nitride with an indirect band gap of 0.9-1.6 eV. [4][5][6][7] It has a rocksalt structure with an experimentally measured lattice parameter of 4.50 Å, 8 a hardness of 21 GPa, 9 and a high temperature stability with a melting temperature of 2600°C.…”

“…The in-plane lattice mismatch between rocksalt ͑c-͒ ScN and wurtzite ͑w-͒ GaN is less than 2%, for ScN͑111͒ ʈ GaN͑0001͒ and ScN͓110͔ ʈ GaN͓1210͔, making ScN/GaN heterostructures or Sc 1−x Ga x N solid solutions potential replacements for In 1−x Ga x N. 2 Calculations of formation energies indicate that the formation of wurtzite alloys ͑GaN ground state͒ becomes more favorable than cubic alloys ͑ScN ground state͒, for GaN concentrations larger than 65%. 2 The band gap is observed to increase linearly from 2.0 to 3.5 eV with decreasing ScN content from 100% to 0%, respectively, independent of crystal structure.…”

“…Solid solutions, as found in the present experiments, were considered in the modeling using a random metal sublattice configuration rather than the small sized ordered structures that have been used in previous theoretical studies on related materials. 2,23,24 The significance of this treatment for the configurational degree of freedom is described in Ref. 25.…”

Pressure effect on electronic properties of Sc0.5In0.5N compound

“…Theoretical studies of the structural and electronic properties of other ternary compounds have been reported recently [3,11,12].…”