Band gaps of wurtzite Sc_xGa_(1-x)N alloys

摘要

Optical transmittance measurements on epitaxial, phase-pure, wurtzite-structure Sc_xGa_(1-x)N 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 3.37eV to 3.26eV for Sc_xGa_(1-x)N 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 Sc_xGa_(1-x)N band gaps with increasing x is an artefact resulting from the presence of nanoscale zinc-blende inclusions.