Band gaps of wurtzite ScxGa1-xN alloys

Optical transmittance measurements on epitaxial, phase-pure, wurtzite-structure ScxGa1-xN films with 0 <= x <= 0.26 showed that their direct optical band gaps increased from 3.33 eV to 3.89 eV with increasing x, in agreement with theory. These films contained I-1- and I-2-type stacking faults. However, the direct optical band gaps decreased from 3.37 eV to 3.26 eV for ScxGa1-xN films, which additionally contained nanoscale lamellar inclusions of the zinc-blende phase, as revealed by aberration-corrected scanning transmission electron microscopy. Therefore, we conclude that the apparent reduction in ScxGa1-xN band gaps with increasing x is an artefact resulting from the presence of nanoscale zinc-blende inclusions. (C) 2015 AIP Publishing LLC.