Band gaps of wurtzite ScxGa1-xN alloys
Tsui, H. C. L. and Goff, L. E. and Rhode, S. K. and Pereira, S. and Beere, H. E. and Farrer, I. and Nicoll, C. A. and Ritchie, D. A. and Moram, M. A.
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 I1- and I2-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.
Department of Materials
Imperial College London
Royal School of Mines
London, SW7 2AZ - UK